get a soldering iron if you need to weld cracks and Bondo to fill in scratches and gouges from Canadian Tire. You may also need some extra ABS material, get ABS pipe and melt it down or lego works too...good luck
I'll second this. Did it myself about two months ago on some broken fairings I bought off a guy. don't waste your money on expensive fairing repair kits. It's really not hard to do.
The only potential problem with Bondo is that it might fail if you are fixing a section that flexes because I am told Bondo is intended for metal parts that do not flex (am going on second hand information here so don't chew me out if this is wrong). What I used instead was one of those epoxy sticks with one chemical in the center and the other around it. You kneed it like putty and it not only sticks well, it cures just like plastic.
You can get one made by JB Weld all over the place (Canadian Tire, Home Depot, Rona, plumbing stores, etc..)
If you use this to fill in the holes and reinforce the back of the fairing behind the crack, you'll have a section that is even stronger than the rest of the fairing.
I warn you, it will take a bit of time
1- Take a Dremmel and drill a small groove over the crack to make it easier to weld all the way through
2- Weld with soldering iron first from one side, then from the other to make 100% sure it welds all the way through
3- Fill in the remaining groove space with extra pvc if you have it, with epoxy, or with bondo
4- Sand the outer surface of the fairing smooth (you can leave exra material on the inside to reinforce it)
5- Paint
With new fairings at $600+ it can be well worth your time to do a couple hours of work. I ended up wrapping my fairings with carbon fiber after I did this.