two places i've ordered from:

1. http://www.everyonedoesit.co.uk/
I got a cheapo bong from this site. It leaks around the bottom and every couple months I have to use a tube of silicone to reseal it, but it works well for the price i paid.

2. http://www.collectpipes.com/
i got my pipe from here. i've used it pretty much daily for the past year with no probs other than resin build up. they have a section of cheap pipes as one of their product categories.