I've been using this cheap method for many years...usually arisol-cans costing aus}$40 for primer, gloss black,clear gloss...in this example. I forgot to seal the primer as I was not sanding what was left-off as the MTB-frame needed it and instead did-3-grays-3-blacks-3-clear coats and this without heat-lamps and being winter I await for a day for curing before each stage and without hanging-racks on doing it outside my unit on a goat-hanger...depending-on-if the paint has gone-off or that the frame has wear scratches and marks on it, as primer saves time rather than using auto-puddy.
The brand name of this paint is "Motospray" in Aussie. I'm doing two frames being both bought as complete bikes for $20 each... one chromolly shogun and the other unknown steel frame...one is my replacement frame (guess which one?) and the other another motorized bike build.