If you are asking this in response to my comment in your other thread, thanks for listening.
I would Google aqauarium clubs/ societies in your area, they normally list their events on their websites. Down here you don't have to join the club to attend the auction but check or you may get hit with a membership fee too. I might go to one myself soon just to check it out, I've heard they are fun and sometimes you can get some good fish direct from the breeders too. If you want to become a hardcore aquarium keeper it's a good place to start making contacts and get some good firsthand advice.