i had kinkos print out the art for my 2/3 scale galaga. I took them 300 dpi art, and they printed it out on vinyl for me. They charged me $6 for each piece (kickplate, cp, sideart), and it looks like a million bucks. I was seriously blown away by the quality, and the picture doesn't do it justice.
I think they can do a test print for you or something. I took my art in PDF format, because thats what they told me the format the vinyl printer takes (I didn't want them to convert anything and possibly screw me up).
I know people haven't had the best experience at kinkos, but there is no way I'm going to pay any online printer 10X more (I can't imagine them doing any better).