Wow. I’m sorry, but that’s kind of sad. You can get spray paint almost anywhere. They have it at Home Depot, like any hardware store, or even at a lot of drug stores. You can get a can of touch and tone for like $2 at a drug store.
Also like Mr. Tubb said if you can't buy legally have a parent or someone over 18 come with you.
I have a topic with complete instructions on how to make a bladder out of a bike inner tube.
Just go to forums, homemades, and look for a Pressure bladder now, gun later.