I use exactly 2 screwdrivers for anything pinball: A flathead for anything Gottlieb, and a medium sized phillips head for pretty much everything else, and I've been able to service nearly every game I've ever come across with them. They're both the most standard run-of-the-mill screwdrivers, and I think I paid only a couple bucks each for them at harbor freight. I guess if you're going to use screw drivers for a ton of different things, it could be worth it, but for pinball, that sounds like overkill.