If nuts and bolts is all you are going to do I may have a suggestion for you. We bought a vibratory tumbler and have tried a few different medias, but they take so long. I am not discrediting them, I know a lot of people that get great results from them. It just takes a little more time than we want to spend on some parts. I have done some research on electro-polishing and we actually purchased a small kit and experimented with it a little. The results were really cool. We took a stainless steel striker bolt that we had turned on a lathe a "dunked" it in the solution for less that 30 seconds and it came out looking like it had been polished on a buffing wheel. I can't remember the pricing, but I think it is real comparable, if not cheaper, than a vibratory tumbler. This may not prove to be true if you start doing larger parts, but for nuts and bolts it is worth researching. I will try to get the company name that we went through and post it here if I find it.