I got 3 10' sections plus a 2 ' section, plus about 15-20 loose roller from the local scrap yard. I think I paid $20 for the lot. All the frames are kinda bent,and the rollers are too close together,thinking about making some out of angle,spacing the rollers 6in apart.
The neat thing about factory rollers that I haven't seen mentioned here is that one end is spring loaded for easier insertion in the frame.
