Crystal Infused Leather, aside from sounding very cool, is used in most high level Leatherworking recipes. Want to get a higher level? try WOW power leveling service at VCSALE, also you can buy WOW gold and WOW cdkeys.
However, it's kind of a specialty item in terms of where it comes from. It sells anywhere from 10-15 WOW gold per stack on my server, so it's worth it to grind for it. It's not very hard, either!
Head to Hellfire Peninsula, and grind on Quillfang Ravagers. Kill, skin, rinse, repeat! Hold onto the Fel Scales they may drop, and keep your fingers crossed for greens! This is a somewhat out of the way spot (check the map for location), so don't worry about too much competition!
This isn't fancy: skinning is a straightforward deal! File this info away into your list of good WOW money grinding spots, or for when you roll a Leatherworker. ;)