The product you want to by is called
3M™ Scotchlite™ Reflective Graphic Film 680. That link takes you to the 3M Canada website, but the same product is sold in the USA & worldwide.
The 680 film is available in many different colours. I have always used black, which appears black in daylight but reflects brilliant white at night. The film is also available in different roll sizes - about 15 inches wide for tractor-feed film cutters, 36 inches wide for other applications. It is not expensive, enough to fully cover saddlebags, etc. will likely cost you about $20. The easiest place to get it is from a local sign shop, although if the sign shop doesn't have it in stock, look for a distributor who supplies sign shops.
The big advantage of using the 680 spec film is that if you apply a LITTLE BIT of heat to it, using a hair dryer (not a heat gun), the film becomes very flexible and you can easily wrap it around compound curves to achieve a very professional looking installation. To prepare the surfaces for film application, wash the motorcycle with your usual detergent & water, then lightly wipe the surfaces you will be applying the film to with rubbing alcohol to remove any contamination that might remain on the surface.
See this post:
Reflective Tape Ideas? for a picture of what the 680 film looks like on my ST 1100, both daylight and night photos. This post:
ST1100 Front Fork Paint shows additional photos, including a photo showing how to apply the film. This post:
Painting wheels and fork legs shows the same film on the front forks of my ST 1300.
Michael