I put 50 cents acrylic paint on my car, and it's stayed for over a year. On a car. That's outside in the rain and snow, and ice. :B
I've used it on wooden buttons as well.
My mom used spray paint on vinyl, I think - for a Halloween costume from a long time ago - and it stayed.
If you want it to look less matte, try a gloss to paint / spray over it.