they sell them online..a decent one is about 20-30. Just check around, most of the pipe selling sites have them as well.

If you don't want it shipped, you can always just check in your local pipe shop, or a friend may be wanting to get rid of one, so you can ask around about that too.

A decent one that goes to .1 should only run you between $20-40. Don't really pay more than that unless the screen is big, backlit, and goes to .01.