I've had pretty good luck with the durability of duracoat.
As far as the price goes, it's almost $40 to buy the stuff you need, so if they provided the paint $50's not a bad deal.
Granted, when you buy it yourself you can paint like 2-3 long guns (I've never used it on a pistol) but it doesn't keep well once mixed, so unless you have a bunch of stuff you want the same color, you're not going to save much by doing it yourself.
You can also retouch it really easily, so I wouldn't bother babying the gun. Me and a few friends go in together every few years to buy a can and coat our hunting guns. That way, we don't have to worry about them rusting if we don't get the rain out of every crevice.
Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety. ~B. Franklin