This is what you want:
It's pretty much the "standard" paint. Available everywhere and cheap too. I think you can get a can for something like $4.
You can usually get the regular semi gloss stuff anywhere but the camoflauge/ultra matte line is a bit harder to get (I know some army surplus stores have the camoflauge line but don't usually carry too much of it cause it's not their main business).
Really when I say Krylon I mean any general spray paint. Kind of like how a "Frisbee" isn't really a Frisbee unless it's made by "Frisbee" any other brands are technically supposed to be called "ultimate discs".