I paid $20 for the Camco Awning Tape at the RV dealership and it would not stick to the underside of the awning. I washed the area, used rubbing alcohol like the directions stated. it came off within a couple days.
So I went to the local hardware and bought the "Gorilla Glue Tape" ($8) and so far it has held up to weekly open and closing of my awning. (I repaired 4 holes or small slits) I also had a wear mark on the awning from the door opening, from lowering one end of the awning during rain. Otherwise it shouldn't touch the awning! I put a strip of the tape over the wear mark to keep it from getting worse.
Hardware,Walmarts and I believe Joann Fabric sells it...if so, you can use a coupon!