keep in mind, if you go Scooter_Trash's route and get the reusable aerosol gun (no offense intended just giving advice here, it is a good option), you won't just be needing paint. Based on what type of paint you use, whether it be base coat/clear coat, acrylic enamel, full-thane, etc. you'll need solvents to go with that paint in order for it to spray out of either the reusable aerosol can the same as you would an actual paint gun hooked to an air compressor. The paint won't be thin enough to spray otherwise, and there won't be any hardening agents for paints such as acrylic enamel or full-thane. I do paint and body for the public on the side and as my day job, I am a paint/body man for a trucking transportation company here in my area. I'm just trying to save you a headache, and with refinishing, even touch-ups, you get out of a job what you put in it. Find a local automotive paint supplier in your area, talk to them about the products they carry, and make your decision based on their recommendations. If you go to one of the big name parts stores, for example, Advance Auto Parts, they'll try to sell you their pre-mixed Duplicolor ready to spray paint. I've heard some pretty bad reviews on the paint on how it doesn't cover well at all, and as far as finish and durability, I couldn't tell you. I would just hate for you to end up with a paint job you aren't happy with. If you plan on keeping the bike, I'd take the time to do it right the first time if it were mine. If you plan on trading the bike off or selling in the near future, you have two options- you can either do it right and not have somebody point it out to you when they come to look at it and try to get you to lower your asking price, or you can do it the cheap way and take a loss. Just friendly advice- take it for what it's worth. Good luck, whatever you decide. Ride safe.
Oh, and as far as parts stores go, if you have an O'Reily's Auto Parts in your area, some of those stores (I know ours do) mix paint for aerosol cans for touch-ups. Pretty reasonable prices, and our stores offer some of the same paints and products that the paint supply stores do. Just ask them about it.