What kind of paint do you want? What is the results your looking for? If you just want something that looks good for now and the car won't be a show car and you want the cheapest paint possible go to your local paint shop and get a one stage paint of your choice of color and brand. If you want something that will look good and hold up to scruteny go to your local paint shop and ask for a two stage paint of base coat and clear coat of your choice of color and brand. I recomend PPG for either because its good paint and the easiest to apply in my opinion.
I wouldn't think of a) painting with anything but two part catalyzed paint (I use PPG too; never had problems with it) and, b) buying paint from anyone other than my local paint store. There is so much information you need besides air pressure setting that it is folly to not use an expert for advice. Paints change almost daily. If you figure your labor and other costs, even the $100/gal which good paint is approaching is the cheapest part of the job. If you are to the point of cheaping out at this stage of your project, you can get the real cheap stuff at your local paint store. Western brand paint is about half the price of the good stuff and looks shiny for at least a year before it goes bad.
Incidentally, the ridiculous price of auto paint is 100% the fault of the Federal government. Their stupid regulations are driving paint prices thru the roof with the goal of total elimination of do-it-yourself paint very soon. If you don't believe that is coming, go talk to your paint dealer. Keep voting for Bill an Hillary and that gang and you and your Komrads will soon need government permits to burp.