iFixit now has these in stock:
Front panel glass/digitizer and LCD screen for iPhone 5. Does not include home button assembly, front camera assembly, earpiece speaker, or the LCD shield plate. — 50+ available at 54.95 each.
Glad to hear I'm not the only one to damage the iPhone 5 so quickly!!
I got my screen on Saturday from RepairsUniverse here - iPhone 5 Screen. It arrived yesterday and my iPhone is now like new again.
Got the case too so hopefully it will last longer 2nd time round :)
Do It Yourself
Arguably the trickiest option here and one that’s only right for those happy to open up their beloved device and void any remaining warranty. Depending on your model, this can either be remarkably easy or a bit of a drag. The iPhone 5 made it a lot easier to replace the display assembly but replacement parts are still very expensive at over $200 at least for the front construction. Remember – you cannot replace only the glass but you must replace the whole construction: glass, digitiser and LCD included. If you were to buy this replacement iPhone 5 screen at around $ 87.88, you could save around $80 on the Apple cost by repairing an iPhone 5 yourself assuming your time is free.