A lot hammers down at $1,000. Simple number. Now watch how many different people take a piece of it before anyone walks away happy.
The buyer doesn’t pay $1,000 — they pay $1,180. The seller doesn’t receive $1,000 — they get $850. And somewhere in the middle, the software platform quietly takes $50 to $80 off the top. That’s three different fees riding on one hammer price, and if you’re the auctioneer standing between all of them, you’re expected to explain every one to people who’d rather you didn’t.
Most fee confusion isn’t dishonesty. It’s that the numbers on an auction get talked about as if they were one thing. They’re not. Let’s take them apart.
One hammer price, three fees — who pays what
Every online auction sale comes down to four numbers: one hammer price, and three separate fees stacked on top of it. They flow in different directions and land on different people.
- The hammer price. What the auctioneer says when the bidding stops. This is the reference number everything else is calculated from — but almost nobody actually pays or receives exactly this.
- Buyer’s premium. A percentage added on top of the hammer, paid by the winning bidder. If the premium is 18% and the hammer is $1,000, the buyer’s invoice is $1,180 (before tax and shipping).
- Seller commission. A percentage the auctioneer deducts from what they remit to the consignor. If commission is 15%, the seller nets $850 on that $1,000 lot.
- Platform / software fee. What the auctioneer pays to run the sale on someone else’s system — and the one fee in this list the public never sees.
Buyer’s premium and seller commission are your numbers. You set them, you disclose them, you keep them. They’re how an auction house makes its living, and there’s nothing hidden about them when they’re printed in your terms. The fee that causes trouble is the third one on top — because it comes out of the same pot, and it’s usually structured so it grows exactly when your sale goes well.
Buyer’s premium: the number that surprises new bidders
Buyer’s premium is standard practice and has been for decades. Online, it commonly runs 10% to 18%, sometimes higher on specialty sales. A bidder who’s new to auctions sees “$1,000” and mentally spends $1,000. Then the invoice says $1,180 plus sales tax plus a card-processing surcharge, and now you’re fielding an angry email.
The fix isn’t a lower premium. It’s disclosure that hits before the bid, not after. State the premium rate on every lot page and in the registration flow, in plain type, not buried in a terms link nobody opens. A bidder who knew the premium going in doesn’t feel cheated; a bidder who found out at checkout does. Same number, completely different phone call.
Seller commission: your actual margin
Commission is the cut you keep from the consignor’s proceeds — typically 10% to 25% depending on the category, the consignor relationship, and how much work the lot took to catalog and sell. Combined with buyer’s premium, this is where an auction house’s revenue actually comes from.
Here’s the thing worth being clear-eyed about: buyer’s premium and seller commission are both charges you control. They’re disclosed, they’re yours, and they’re how the business works. The problem is never these fees. The problem is a third fee that behaves like commission — a percentage of every hammer — except it goes to your software vendor instead of your bank account, and it isn’t on any invoice you show anyone.
The platform cut: the fee nobody quotes you up front
This is where auction economics get murky, so let’s be specific. Two very different kinds of company call themselves “auction platforms,” and they charge in two very different ways.
Marketplaces — HiBid, Proxibid — sell you access to a huge pool of registered bidders. That reach is real and it’s valuable; nobody should pretend otherwise. But it’s priced as a cut of your success. As of 2026, based on public information, a marketplace like HiBid typically charges the auctioneer a percentage of hammer gross — roughly 5% to 8% — plus per-lot listing fees, with the exact rate negotiated by tier and volume. That percentage is a third hand in the pot, sitting right alongside your buyer’s premium and your commission, taking its share of the same $1,000.
Run the math on a working auction house and it stops being a rounding error:
- 50 lots, $20,000 total hammer, once a month → roughly $1,000–$1,600/month in platform fees.
- 200 lots, $80,000 hammer, four times a month → roughly $4,000–$6,400/month.
- 500 lots, $250,000 hammer, weekly → roughly $12,500–$20,000/month.
The structure has a specific quality worth naming: it costs you the most precisely when you do best. A great sale with strong hammer prices is a great sale for the marketplace too, because their fee is a slice of yours. You did the consignor relationships, the cataloging, the marketing, the ringwork — and the percentage rides along regardless.
To be fair, that’s the deal for reach. If a marketplace’s registered-bidder audience is what’s bringing buyers to your lots, the percentage is buying you something concrete. We’re not going to tell you those fees are pure waste — for a lot of auctioneers, that audience is worth paying for. Just know what you’re paying, and know that it scales with every dollar you earn.
“Call us for pricing” is itself a data point
The other kind of vendor is the white-label platform — software that runs your catalog and bidding under your own brand, without bringing an audience. BidWrangler, NextLot, AuctionFlex, and others live here. Some are genuinely good tools with years of polish.
But try to find out what they cost. AuctionFlex’s pricing is “call for a quote.” NextLot’s public pricing is thin. BidWrangler is reportedly in the $200–$500/month range plus per-listing add-ons, but you’ll mostly find that out by getting on a call. As of 2026, based on public information, most of the legacy white-label vendors publish very little.
“Call us” isn’t automatically a scam — enterprise software does it constantly, and sometimes there’s a real reason. But for a tool aimed at owner-operators, opaque pricing usually means one of two things: the price flexes based on what they think you’ll pay, or there are per-lot and per-listing add-ons that make the sticker number misleading. Either way, you can’t compare vendors you can’t get a number out of. When a vendor won’t print the price, that reluctance is the answer to a question you should be asking.
Read the whole stack before you sign
Before you commit to any platform, get these five numbers written down — not implied, not “we’ll work it out,” written down:
- Monthly or annual base fee. The flat cost of having the tool at all.
- Setup or onboarding fee. One-time, but real. Ask if it’s waivable.
- Per-lot or per-listing fees. These are the ones that quietly scale with catalog size.
- Percentage of hammer, if any. The big one. A 5–8% cut of gross dwarfs any monthly fee at real volume.
- Payment-processing fees. Card processing is a genuine cost, but confirm whether the platform marks it up on top of the processor’s rate.
Then do the arithmetic against your actual volume, not a demo scenario. A vendor that looks cheap at 20 lots a month can be the expensive one at 400, and vice versa. The right question is never “what’s the monthly?” It’s “what does this cost me across a full year at the volume I actually run?”
Where Hammerwerks fits — honestly
Hammerwerks is the workflow software — AI-assisted cataloging, your white-label bidding catalog, settlement — not a bidder marketplace. We don’t have HiBid’s audience, and we don’t pretend to; plenty of our customers run both, using the marketplace for reach and us for the catalog-and-settlement work underneath. What we can be flat about is our own price, because that’s the fee this whole article is about. It’s published, it’s the same for everyone, and there’s no negotiation: Standard is $499 one-time setup, $99/month, $49 per auction — founding customers pay $0 setup and $49/month for six months (then $99), and their first auction is free. Unlimited lots and bidders, 30-day money-back. No percentage of hammer. No per-lot fees. Your buyer’s premium and your seller commission stay entirely yours, the way they should. If you want to see exactly what a sale would cost you before you decide anything, watch the 90-second demo or book a call and bring your real numbers — we’ll do the arithmetic with you.