If you want it too last, buy the lower grade automotive paint with a hardner. It will stand up and last, but you'll still spend between 100 and 150$ to get some primer, paint, reducer and hardner.
Lots of people take the easy way out with spray cans, but to me it's a ton of work tearing apart a bike so do it well if you can.
You can also get into powder coating for under 150$ for everything you need (aside from the compressor) and grab a free oven off of Craigslist. It was the best thing I ever did!!
I have a couple pieces of large commercial ductwork that I'm going to swap the oven elements and t-stat into it and be able to coat frames.
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country