Check sherman williams if you've got one of those somewhere close. You can get a hell of a deal if your buying a large order usually. Duraplate 235 is what i'd check on.
Duraplate 235 is a two part epoxy based paint, It can be sprayed with a "wee-waw" type pump, or you can hand mix 4:1 and roll/brush it on. Spraying gives the best looking results but either application method will give you a durable, lasting, hard finish that will last for years in your environment. It's made for painting ships, corrosion resistant, very chip resistant, stinks like hell until it's cured, be sure to have proper ventilation while painting it.
If you spray it, don't forget to have MEK or very strong thinner to clean your pump/lines out with, this shit doesn't mess around once it's hardened, mechanical removal is the only way after it cures.