http://www.art-pipes.com/
Cheapest prices on the internet, plus the guy throws in lots of freebies. The only sketchy part is that he doesn't accept credit cards and you have to ship him money. But it's reliable and fast shipping. I just bought a nice bong there and he threw in a free bubbler, grinder, and one-hitters.
Everyonedoesit is a good one but pricey. Good name brand shit tho. I still prefer Venice Beach or the local SoCal headshops. You might get a freebie online, but you can haggle and get discounts in person.