So when you bought that pink K5 from the 7up commercial, they didn't give you the tires with it?
I've done all three methods. Rattle can, roll on, and cheap HF sprayer ($15? for the gun)
A cheap sprayer is the easest way to lay down a lot of paint, good coverage, and good results. Problem if you don't have a compressor, or have a compressor that will keep up with the
CFM. I used my buddies, can't remember what CFM it did at the PSI my gun required, but 110v, 40gal. Could barely keep up, had to stop and wait on big things like the hood. When I was done with the truck, so was the gun.
Rattle can is super easy, but if there's any breeze, you're screwed. Like 1/4 of the paint will get on the truck, and it'll be thin, breeze or not. Figure what you need, and double it. To give you an idea, I used two cans on just one door and wished I used a 3rd. That was a door though I took to bare metal. Good thing about rattle cans, do what you can, or have time for that day, do more tomorrow. When you're done spraying, toss the can in the trash, no clean up. Do a door today, a fender tomorrow. Down side of the sprayer is cleaning the bastard!
I rolled the bed portion of my 68 GMC pickup, it put on a lot of paint, I didn't even thin it like most roll on 'how to' articles, and it still turned out really good. DON'T do what I did and forget to use a
FOAM roller

I forget how long it took me to sand the lint out. The only down side if you don't thin the paint, is you'll get a lot of orange peel, and w/o using a hardener, it takes weeks before you can sand.
I bought basic rustoleum that was some shade of blue cause it most closely matched what color the truck already was. I probably didn't use a gallon. I had to buy it in qts though, cause no one carried this specific blue in a gallon nearby. I think it was $30 at Lowes for a gallon? Pints were like 9-12, I forget. Going cheap, just use rustoleum. They have gallons of primer too if that's what you'd like to do. BTW I didn't sand this to metal, OR prime it. It was just my first attempt (other than the rattle can) to get a decent finish. Only spots I primed was where I was rusting and took it to metal.
Here's a pic of the truck I painted, HF spray guned all but the bed. Rolled that on.