Well, you could try a poly-urethane laminate (PUL) fabric and do it yourself with Rit (or similar dyes) or buy ready coloured.

Have a search for PUL diaper cover fabric online, it comes in a ton of colours and some of the fabric (ie most backing polyester fabric) won't crinkle but I would suggest you check with the seller first. To keep it wrinkle free, roll it around a cardboard tube when storing it.

You could also use vinyl - however this will be shiny, by using a PUL fabric, you could use the coloured fabric side rather than the reflective PU laminate side.

I've not tried it with photography but I am familiar with various forms of PUL fabric and can't see any reason it would not work as an inexpensive lightweight, waterproof and pretty durable backdrop.

In fact, if you go to a fabric store such as Joannes or I think Michaels (can't remember I am not actually in the US) and buy wrinkle free fabric that would be cheaper than a genuine backdrop from a photography store. If you wanted to have it PU laminated a company in the US www.fabrite.com will coat it for you. The reason i suggest teh poly urethane coating is that it gives a bit a strength and durability (like a flexible plastic coating) to thin lightweight fabric.

Michelle