Where the hell can I find a triwing screwdriver?

I opened up my Gameboy Color to make some adjustments, and now I can't put the screws back in. I used a knife to unscrew the screws but I can't do the same anymore to put them back. I have no credit card so don't suggest somewhere online...I need either a substitute for a triwing screwdriver that works, or a store that i can check out and find one at.