Not bad business if you can get it.Close. Sellers pay an entry fee and commission; for No Reserve lots, it’s 8%.
https://barrettjacksonvip.com/blog/how-to-sell-a-car-at-a-barrett-jackson-auction
The buyers premium is 10-12%, and is added to the hammer price.
https://www.barrett-jackson.com/pdf/bid/AutomobiliaAuctionTerms.pdf
On a $100k hammer price, Barrett collects $115K -$117k, sends the seller a check for $100K, and retains $10K-$12K in earnings.
One event last year grossed $131M for ~1800 no reserve lots. That event grossed about $24M to B-J.