How expensive to replace the slide out awning fabric?

Absolutely best replacement topper material is available from Stone Vos in Brooksville, FL.

Many folks also recommend Tough Tops for slide topper replacement.

Regardless of where you get the material, it is not hard to R & R. As noted, you need a couple of good ladders and a second person if the toppers are long. There are a number of You Tube videos showing the process.

I would estimate 500 each, but you can do better by pulling one slide right out and reading the label on the very first wrap. Take a close up picture with your camera of the label, and then look up the replacement.

I did a 6 foot unit by myself. You really need two people on two tall ladders or alongside a wall or platform (best option) as once you start to put it in, you can't stop. Study the U-tube videos to see how to do it.

Lot's of spring pressure there, but OK if done properly. I also replaced a garage door spring in my house.

www.shadepro.net/category/Replacement_Slideout_Canopies.html

Try these guys. I replaced one of my longest ones on our Phaeton with the acrylic fabric. Nice material, cost less than $250 and wasn't hard to do, especially if the old one is still in place. Go on their web site. You can call them as well to get sample material.