I don't recommend painting any case. The results will leave you with a case you can't sell. I would sell it on craigslist and order a new one when they are on sale. Frys sometimes gives away cases after rebate when they clear out their inventory.
The nicer cases have baked on paint for a harder finish. It's going to be difficult for you to duplicate the results of a factory finish. I often find some funky off color cases that are closed out for half their original price. I would also check your local goodwill store or craigslist for a cheap case to practice on if your case is still in good shape.
Remember prep is the key, completely disassemble the case and take care of any bumps or scratches first.
Thin layers is better than one thick coat. Lightly sand after the coat dries using 1200-1800 grit paper to take care of any runs. use 3000 grit paper on the final layer then a polish followed a thin coat of automotive wax for a fantastic shine. Final coat can be a clearcoat if you want a car-like finsih. You'll be surprised what you can do with a can of spraypaint.