Our Auctions don't currently have a 'buy now' feature, as we've seen that actually reduces the amount of money that organizations can raise!
We’ve found that using the 'Max Bid' feature often results in items selling for more than their fair market value.
With that said, if you're looking to sell multiple of an item (say, t-shirts, for example), our Impact Giving tool is a great option and can be added to your auction!