I have shopped from almost all of them. Being my favorite, Petmountain.com probably has the cheapest prices for most items, but they do not have the largest selection. I got my aquarium freshwater T5HO lights from marinedepot.com. You don't need T5HO unless you want plants. Otherwise it will just cause more algae. Fish don't need lights the same way the reptiles do. Most of their food are fortified with multivitamins.
I actually have a small multitask device to tell me the humidity. It is uselessly inaccurate, and I never take its reading seriously.
