Stupid question - diamond plate

So I've seen a lot of Jeeps (and other vehicles) where people have attached diamond plate to the body (usually to cover up rust spots). I'd like to do something like this to my Jeep (cheaper than replacing the body) but I wouldn't know where to begin. I was thinking about that black diamond plate. I have seen pre-cut plates you can order but they seem to cost an arm and a leg. Shouldn't there be a place where I can just buy the stuff (Home Depot or something?) where I can give them the dimensions to cut? Where do I find a place that will sell and cut diamond plate to a guy like me? And how is the diamond plate usually attached to the vehicle? Bolted on somehow or just glued on? Would I have to have someone do the job? Sorry for the stupid questions, I've never dealt with this stuff before.