We get requests for iPod Touch 4G repair for cracked screens and water damage all of the time. The truth is, they are all kind of a pain to fix compared to their smartphone cousins. That coupled with the price of the 4g digitizer itself and it is something to think twice about in terms of DIY.
One additional note is that the majority of people breaking the iTouch are kids and they are addicted to their favorite Apple device. Recently we ran out of iPod Touch 4G screens after being flooded, all at once, with parents whose kids broke the screens.
We ran out of the iPod touch screens and some parents were left to wait for them to come in stock. It turns out the future of tomorrow wants their iPod Touch fixed and NOW! We totally understand and will do all we can to insure we have them in stock.