I've been going to only a couple of real fish stores over the last 20 years, The Fish Store in Ravenna (now in Lake City), and the Aquarium Co-Op, in Edmonds WA.
I am thankful to Google for finding this little hole-in-the-wall 2 miles from my home. Large selection of fish and plants as well as great advice. No nasty emplyees/owners here.
If you're a member of the Greater Seattle Aquarium Society, you get a 10% discount. If you're not, you get really good quality - which you have to pay for. If you want crappy quality, go to Petco, etc.