Check out West System Epoxy, they make some of the best materials and have outstanding technical support (free, you just pay for the phone call) AND they have booklets and videos available if you need them.
Forget about gelcoat, you need regular epoxy and fiberglass and "regular" patching. If you want to disappear the damages, and bring them back to full strength, typically you grind them out so the surface tapers at a 1:12 taper down to the hole (i.e. if the hull is 1/16" thick, you taper out 12/16" around it) and then you build up the area with fiberglass and epoxy. Then finish it after all the work is done, which probably would mean repainting the canoe with a two-part urethane paint.
West can walk you through all the details, if you want a truly "better than new" result, that's how to get it. Under $100? Don't think so. You can't buy a canoe for under $100, much less the materials to refinish it. That might buy you materials to repair the damages properly--but not enough to refinish it as well. Maybe $200.