Before you shake off the idea of repairing your cracked iPhone screen yourself with a kit, consider Brett. The crafty 10-year-old repaired the cracked screen on his father's 3GS with a $US22 mail-order kit, giving all of us a little more confidence.
To be sure, Brett's a crafty kid who comes from geeky roots. But by patiently taking apart the 3GS, sliding out the cracked glass and replacing it with a repair part from 3GCrackedGlass.com, Brett was able to save his dad the cost of buying an entirely new iPhone. This repair was for the glass only, as the LCD wasn't damaged and the phone was otherwise functioning — but that seems like the type of repairs most iPhone owners need.
Hit the link for a photo gallery of Brett's repairs and more detail on what happened. If you've drawn repair inspiration from another younger (or older) relative, we love those kinds of stories in the comments.