I purchased it from stickerboy.net. They ship very fast too. I was able to get 5% off with this discount code: "bestskins". I entered the code at the final page of the checkout process.
I have no idea exactly how thick it is but it's definitely enough to provide adequate protection from scratches. I just took a picture of two more skins that I also purchased for later on when I get tired of the other color. You can get a good idea from the close up picture how thick it is.
The smart cover doesn't overlap the skin so the magnetism isn't affected at all.