The last kit I bought was at Pep Boys for about $8. Had resin, hardener, and glass cloth. Everything you need.
Go to walmart and buy the big fiberglass sheets. They sell them in the boat and automotive section. Then get your favorite epoxy and mix it up and apply it to the fiberglass sheets and go to work. You might want to sand off the paint where you're going to do the repairs though to get a strong bond.
Any boat place like Boats US or E&B Marine will have the best selection of fiberglass products. You dont want to put a wooven type mat on it. Instead get the stranded type and cut it up. I would bet they would have "how to" videos there too.
I used to help a guy eons ago (early 70's) repairing and painting corvettes for the Tidewater Corvette Club. We always used the fibers for repairs like that. The only time we used mat type was if there was room, we'd lay some on the back side for strength or if the piece was cracked in half. Mat type is definately stronger but the fiber is easier to work. Of course, I was just the laborer and the other guy was the "expert" so I wouldnt bet my life on this. Its just what I was used to doing.
I have done mucho fiberglass work. Stranded is the way I would go on that repair. If you go to an autobody supply store, you can get good tech info from a knowledgeable person behind the counter. Dan
Eons ago (early 70's) I helped a friend rebuild a Corvette fender that had a huge hole in it. We used his mother's fiberglass curtains! I always wondered if someone would sand down the fender if they would see the lace pattern.