I was going to suggest the same thing. I've bought it from this website:
www.identitape.com
You might want to call them, though. I got some white reflective tape from them that was really stretchy, so it was pretty easy to apply to curved surfaces like your fenders, but other colors --the yellow, in particular-- didn't stretch at all, so wasn't as easy to apply.
They also have sew-on reflective tape you can sew to your trunk bag if you're so inclined.
For some reason my work is blocking the identitape link, but I've seen other sources. I'm sort of concerned about the seams being super obvious if I went the tape route, but it does seem a lot easier than painting.