My main ride is about 10 years old and has been drenched in salty sweat without mercy during that time. It was coated with automotive paint (epoxy primer, base coat, urethane clear) but even at that I've had to do a touch-up a few years back due to corrosion around the bottom bracket. Common rattle can paint (not Spraymax) has about 25% of the durability of good automotive paint when it comes to corrosion protection. To each their own, but in my view building a frame and then skimping on the paint is bad juju. I'd rather get the thing powder coated.

BTW, Transtar epoxy primer is good stuff and relatively cheap compared to some of the alternatives. And for my last project I used House of Kolor base coat and USC01 clear. The clear is the low VOC type which isn't my first choice, but that's all that's allowed in my area. It takes three coats to get good film build whereas the older 3.5 VOC clear took two. Wonder if the environmental regulators know this?