i use the krylon camo paint for my markers. it holds up pretty well and dries very quickly. it also is a very flat paint, little to no glossiness, but it comes clean easily. i havent had a problem with getting dirt and paint off of it after a day out at the field. when it does wear down, usually in the corners around edges and what not, it actually looks good. i have 4-5 markers and a rocket launcher painted with it.
the other paint i have had success with is Duplicolor's ceramic high temp paint. dries fast and leaves a consistant finish without too much effort. it also is flat and comes in various colors.