I like www.Petsmart.com-it
is convenient and items are fairly easy to find which says a lot b/c I am computer-dumb. Yea, they charge extra shipping for litter and food b/c of the weight, but if you sign up for their newsletter, they sometimes send e-mail for $10 off $30 orders and stuff like that. Plus, you save a tiny bit on tax. It usually doesn't end up a whole lot less, but it does allow you to shop from home at strange hours of the night, and they deliver everything right to your door which is especially great if you live upstairs like me.