what diameter are you looking for and what do you want to use them for?
sells some slightly less expensive pipe clamps that will work to hold small stuff, like a guage pod, GPS or CB mic.
Similarly, I didn't want to spend 30 bucks on a tube clamp. McMaster didn't have the size I wanted either.
So, I made my own: http://www.jeepforum.com/forum/f37/gps-mount-roll-bar-797765/
. But then again, I've got access to an engine lathe and material. It took me over a week, working a few hours each day to finish. Thats a lot of wasted time in front of a lathe & mill to save $30....but I learned a lot in the process.
When you think about it...$30 ain't bad at all. Rokmen sells some DIY clamps: http://www.rokmen.com/products/diy_f...be_clamps.html