Custom vinyl decal printing?

I have a creative motorcycle vandalism project in the works (with
the owner's permission.) In order to facilitate this, I need to
have some vinyl decals printed.

Clearly I need something that's clear, waterproof, and relatively
light-resistant. I have a great injket printer with waterproof
ink, so if I can find a good source of sheet vinyl I can print them
myself. Or I can have them professionally printed.

I also need solid white, but I won't need to have it printed.

Cost is an object, but dirt-cheap isn't. I don't want to spend
an arm and a leg, but I'm willing to drop a few bucks on doing a
good job.

Suggestions?

-Patti