I'm not an expert on alternatives to oxy-acetylene. I've heard that the hardware store oxygen tanks run out fairly quickly. Also, in my previous post, I was thinking of air-acetylene, which avoids the expense of oxygen.

I was thinking about going with propane-oxygen, but then I got a good deal on a O/A torch. For my money, I wouldn't compromise. Building frames and even racks is fairly expensive, the torch/tanks for a decent setup are $400-600 and well worth it.