I was wondering really fast about cutting steel. For fabbing up rocker panels and tubing stuff, how do you cut the steel? Plasma cutters are a little out of my price range here. What is the best tool to use? Thanks for saving my leatherman, Josh Brown

Time to spend some money. Different shapes and thickness' require different tools to do the job. Its endless, but pleasant. Just spend the money. Some applications you can get buy with a hand shears (thin sheet in small quantities). Tubing can be cut with a hacksaw that has a good, high quality blade. When you start cutting any large quantity, power is better. A Sawsall or similar device will cut pretty well. The battery powered ones are great except the battery doesn't give you much working time on a charge. Even a power scroll saw can be used in a pinch. If the surface is unpainted you can use a torch. A real pleasure to use.

A visit to your local flea market can often turn up a cheap die grinder. I've seen them as cheap as $10. Don't expect it to live a long and productive life, you get what you pay for.
If you attach a cutting wheel (whizz wheel), and you have good control over it, you can do amazing things. I'd suggest you practice before you cut into valuable steel.

Maybe the most valuable tool is a case of beer. With that you can sometimes bribe a friend into doing hours of work for you. There are all sorts of devices for the tasks at hand, including things like files to smooth the edges.
Since you had to ask, I assume you've had little exposure to this kind of work.

What are you thinking of doing for the shap of the rockers? Anything like the AEV or PS ones and you are going to need some sort of 'break' to bend them well.

If you are just looking to use some angle iron or something L shaped a band or Chop saw ( both can be had < $200) would do the trick.

The chop saw is one of my personal favorites. Its like having a Mitre saw for wood that works on metal. Just cuts kinda slow.

I'll have to agree with Dick on the corded stuff. I have a 4 1/2" Dewalt cordless angle grinder. Works great, just as much power as its corded buddy (first tool if seen that can compare like that). But it eats batteries. Luckily my bud got me a Dewalt 15 minute charger and a few extra batteries.

Jason