How much money do you want to spend? It might be cheaper to buy a good used replacement set. If you want to restore what you already have...
Look for a business locally that does 'hard coat' anodizing for the most durable finish. Alodining is another possibility, but it's more of a primer for aluminum... won't last as long and is usually top coated with a durable paint. Some grades of aluminum don't alodine well either. Painting by itself is just a waste of time, including Powder Coating. Some will argue that Powder coating is an option, though I've never had good luck with it and salt water. It only takes a tiny scratch in the paint for salt and corrosion to get in. Soon after the corrosion spider veins will start creeping under the paint and it's all over. You won't have to strip the paint, it'll do it for you leaving you with a useless part, made of white aluminum oxide powder.
http://www.ehow.com/facts_6713942_alodine-vs_-anodizing.htmlThere are kits available on the internet for DIY anodizing, but for the cost of the kit, you might as well just buy new castings. Neither option is exactly hazard free or earth friendly either.
Good luck!