The problem with auctions is the sell price is not set by how much someone is willing to pay for it, but rather what the limit of the second most enthusiastic potential buyer is wiling to offer. So thats two keen buyers required within the short period of an auction run.

Comes down to quick turnover=high risk of low price. If you are willing to hold out for a while better chance of good price. Thats the principle of having a store.