I don’t even know how did I come across it, or heard about it, but this is quite interesting- pretty much like an ebay for livestock- http://www.aquabid.com
I honestly don’t know how this site works and/or the reputation of it. So check it out, have some fun, but puchase at your own risk! Although even with the bidding process, this doesn’t seem to be a particularly better deal than any other store.