According to Apple shaman Mark Gurman, Apple will soon be expanding its iPhone trade-in program to include busted handsets. Currently, the Apple Store "Reuse and Recycle" program lets you trade in iPhones with broken screens or buttons for credit when buying a new phone. It's worth about half face value, with a good condition iPhone 6 getting you $450 of credit.
According to Gurman's sources, the program is now expanding to include devices with cracked screens or broken cameras or buttons. Values are about as low as you'd expect: $US200 ($277) for an iPhone 6, $US250 ($346) for a 6 Plus or a lowly $US50 ($69) for a 5S. You'd probably still be better off replacing the screen at a dodgy store and reselling it yourself, but if you can't be bothered, Apple's one-stop shop is worth the visit.