...I was wondering if anyone knows where I could...
Are you looking for 1k (1 part air/self curing) or 2k (2 part paint+hardener)?
2k is the superior that will last 30 years.
Using a regular paint gun:
Eastwood is a good brand, Restoration Shop or House of Kolor are the same guys (TCP Global) - I got TCP Global for my (just finished) job.
If you live in a city with a really big sherwin williams, they are owned by TCP global and the big ones sell auto paint (but the little ones are just house paint).
Rattle cans of 2k:
Larger NAPA's still mix paint, don't know myself, but you should be able to get 2k in rattle cans from them (red activator button that bursts a tube of hardener inside).
Rattle cans of 1k
Napa, larger oreilly, larger autozone, google maps "auto paint" and see what turns up in your area.
... how much I would need?
1 gallon (of standard 2:1 dilute spray gun not rattle can - so makes 1.5 gallons) was more than enough to do the body 3 times everywhere on a 2nd gen regular cab long bed w/o the inside of the bed (I'm doing bedliner after paint).
Just the hood and grill, well with my gun I kept an eye on the 600ml reservoir all the time and I could get hood and 1 probably almost barely 2 fenders - one coat. If you are doing 3 coats (standard in the auto world) I would say 3 cans.