Cry once over the paint cost, but you won't be painting it again for a long time and it will look good!
A very good point.
Better paint saves money over the long term.
I'm personally fond of barn paint, which is made to go on over unprimed, rough wood.
Save yourself some money and use OSB instead of plywood and/or siding. OSB performs better than plywood while also being cheaper.
This is very much dependent on climate.
OSB down here in the Steamy Southeast *might* last 2 years. Or it might not.
The OSB wall on the Little Monitor Coop needed replacement in less than 5 years despite being sheltered by good roof overhangs and protected with barn paint.