I've bought fish on line and have never had a problem. The one thing to remember though is that the shipping will often cost more than the fish. I once paid $35 for a pair of catfish and $45 for the overnight shipping. To me, it was still worth it.
As far as plants, I swear by lowcoasters stock. No, I'm not partners with him. *LOL
I started a thread in the planted section a while back where I took pics of his operation.
Equipment. I ususally web surf till I find the best price. I've purshased from quite a few and my experiences have been generally favorable. I'll continue to buy equipment on line.