I purchased a q snap frame last December and I love it, I have quilted a king size and a throw size quilt on it and it worked really great. We also looked at building one and priced the parts at the home improvement store and it was going to be almost as much as the one I ordered and we couldn't figure out how to make the clamps pieces with the ridges. I ordered mine from amazon and it had free shipping, here is the link.
http://www.amazon.com/Q-Snap-LF-Floo...quilting+frame It is 65.98 with free shipping. I looked at the instructional link that was posted earlier and they are using 1 inch pvc which I don't think would be strong enough, the q snap I have the pvc is larger than one inch, closer to 2 inch. plus still the problem of getting the ridges on the inside of the clamp pieces. The ridged pieces work really great, it will hold even on the edge of the quilt where it is just the backing or backing and batting so that you can quilt closer to the edge of your quilt.