Mecum & Barrett Jackson are neat to attend, but between the rotating locations and variability in inventory plus the buy/sell fees, BAT is obviously way more favorable for buyers and sellers. BAT provides the same provenance and documentation that you get with the legacy houses, but in a much easier to use interface. You can just hit the /auctions page and start scrolling all types of enthusiast vehicles, opting to register only if you want to bid. They provide 24/7/365 opportunities to bid, versus waiting 2-3 months for an auction to bid, even then you need to jump through hoops and be available during the <5 minute auction window. Plus the social element where anyone can comment on auctions is better than the comment sections on many car sites.
BAT started with a lot of traction on Jalopnik and has since grown to be way more upmarket. How (or can?) can a similar model be applied to other markets such as horse yearling sales-- typically dominated by Keeneland/OBS which hold a few sales per year?