How cheap are you talking? The power-rings on ringtraining.com are 75$ which is pretty damn cheap. If that's too much, I'm working on  two articles, one about making parallettes and one about making your own rings, both for under 20$ or so. I should have them up on the main site by the end of the week, so keep an eye out

I was thinking of just buying circular dowels from homedepot and taping them up for grip and hanging them by some rope off of my deck....I think i should be able to do it for under $20 and they should work just fine for what I will be doing for my strength training.