I used to work in the paint business. Imron is good, but old paint tecnology. These days, it's used on trucks and boats. Imron is a line of DuPont paint and now there are better lines of DuPont, and other brands too (PPG, BASF, Glasurit, Spies Hecker (owned by DuPont), and more). Not all body shops will carry DuPont. The largest wholesale supplier of DuPont paints and Imron in the US is FinishMaster.
Not all FinishMaster locations supply DuPont, but you can go to their website and hopefully one is close to you. Then, you can call the closest location and ask what they sell and recommend. They have computers that should be able to cross reference your Imron code to other lines and companies paints.
http://finishmaster.com/locations.cfm
good luck.