3M sells reflective cloth strips. There are usually a few on e-bay. I know there are other companies that sell it bolts, but I've only found places that sell 500m rolls...

This place:

https://www.cyberglow.co.uk/actinic-frame/index.htm

Looks like they have some cool stuff - check out that reflective jacket with 12 red LEDs! $32.58 aint bad at all.

They've also got 1.5" tall letters and numbers for 91 cents each - maybe it's time for some anti-car propoganda on my bag - I have plenty of space