As for price, I really didn't shop around after I found a good source for any part I needed (ACT). I didn't need too much of the stuff, so price wasn't an issue. They gave me a little catalog I order from. Also, the website is helpful.
http://www.locline.com/
If you are doing lines that don't need to swivel around, I would use PVC. If you want to move things around or lift your returns out of the water to stop the back flow of water when the pumps are on, this stuff is great. You can also use different sized nozzles to increase or decrease the pressure coming out of the line. I have lots of leftover line and nozzles that I play with to alter the flow in my tank.
Mike