Need to replace iPhone screen. Are aftermarket parts OK?
Be willing to spend about $40 for the more expensive ones, because in the end, they'll be worth it. The parts work well, but the ribbon cables are ridiculously easy to rip and tear, so be extremely careful.

The cheaper ones usually have thinner glass, thus cracking easily. Also, make sure you specify either CDMA or GSM when searching for parts as the CDMA parts are different from the GSM ones, and they're not inter-compatible.