We have consdiered doing Online Auctions but there are a number of reasons that we don't currently offer them but below are 2 major ones.
#1 Licensing - Auctions, and Auctioneers, in most cases have to be licensed and regulated. If you go to an auction site and they do not disclose their license or permit information prominently on their web site, I would run, not walk to the nearest exit. Most auctions and auctioneers are licensed by the state that the business is located in, however all state laws and regs are a little different state by state, and then when the auction crosses state lines there is a question of jurisdiction. Legal compliance with all the various laws and permits can be tricky.
Not only is holding an unlicensed auction illegal, the results of that auction are not legally binding.
#2 Laws on Auctioning of live animals/livestock - Each state maintains different laws, rules, and regulations regarding the auctioning of live animals and livestock and once again the question of jurisdiction comes into play. I suspect that this is one reason that large companies such as EBay have tread only lightly in this arena.
All in all, to run an auction site, and to do it legally in all
jurisdictions which may be involved, can be a tricky and costly
undertaking, and some day the axe will fall upon those auction
sites that are not being run in compliance with the laws.