Canga has a good list
I just started about 6 months ago. I bought most of my utensils and such at walmart. Anchor measuring cups, cheap 3 pack of cookie sheets, gloves, cheap butter knives, couple cheap pot holders, and some clamps. I bought my microwave from a used appliance store for $10 (do not use the one in your kitchen!)
I started out with a handful of colors and glitter from lurecraft and also bought a couple of their open pour molds. Personally, I found out I do not like hand pouring but they didn't cost much ($8 or so a piece) so I wasn't out that much. I have since bought an injector and a few injection molds (2 artificial stone molds and 2 aluminum basstackle molds). The stone molds aren't bad but I like the basstackle molds a lot better. Basstackle.com has some very affordable molds and they are good quality, depending on what baits he uses most.
I also just bought some more plastic, I started out with a quart, should have bought a gallon. My last order I bought a couple gallons plus some more color, glitter, and hi-lites.
The absolute basics to get started are plasisol, some colors, some glitter, heat stabilizer/softener, worm oil and some molds (an injector if you buy injection molds). Utensils and safety equipment can be bought at a big box store, and he can add extra colors, glitters, and hi-lites/pearls over time. If he gets into it, he will want more molds and more plastic, he can just order additional colors and such then.