Since there isn't any art on them it would be easy to just have them laser cut. Simple vector trace and you're good to go.

I've had my local Tap Plastics make one-off clear plastics for a very reasonable price. I simply scanned my existing plastic, traced it in Adobe Illustrator, and sent them the resulting vector art. Been a while, but I remember it being around $10.

If you are looking for 2D shapes so that a simple cut-out will do or even simpler 3D shapes which could be cut and then bent or formed into the desired shape I might be able to help out as I have a laser cutter and some associated equipment at home.

I am in the process of making a few slightly more complicated plastic parts for my newly acquired W?D and will post results sometime this weekend as I am still experimenting with various types of glues and glueing thechniques.

Ask around locally as well. Maybe there is a FabLab in a bigger city close to you, they usually have laser cutters and are extremely helpful, at least this is how it is around here.
I am located in Europe and would have to ship from here, but this would only set you back 7$ (insured, shipping takes 2-5 days if not deayed by customs). If you can provide me with scans and measurements of the parts I can trace the for you as well.

Anyways I first want to establish myself here in the forum via the aforementioned thread to come, but if you are interested do not hesitate to send me a PM.

I make those out or polycarbonate (Lexan) that I buy in the scrap bin at Tap Plastics... Just rough cut to size then belt sand to final shape.

I've made one out of Lexan as well. Got a small sheet at Home Depot. Works well if it is in a place that isn't visible. Otherwise, you might want a more professional cut. (I have shaky hands. )