...gets less than you want?
A sale is a contract between you and the buyer.
If you refuse to honour it, the buyer can leave you a negative saying what they think of the transaction, which would not be good if you want to keep selling.
A buy it now is not a reserve, it will disappear with the first bid.
eBay does encourage low start auctions, but always start at a price you will be happy with if only one bid.
