Me and my dad just put some of this stuff in my backyard, we used about 12sq metres and it was about $2000 worth of lawn.
Brad is right, you don't want to use the cheap stuff, it is crap! The stuff i have isn't absolute top of the line, but it is pretty good. It looks great! The only thing i can fault it on is that when you walk on it it sounds like you're walking in a tent... Which sort of ruins the illusion. And you have to make sure you set it up so that water can drain off it because obviously water isn't going to soak in anymore. But other than that it is pretty good!
Definitely not as simple as that. You need to mix concrete in with the sand, we used a 7% concrete mixture. While you are mixing in the concrete you also need to wet it, otherwise it won't all set properly. We spread the concrete out over the top and then used a rotomotor machine to mix the concrete and the sand while spraying it with a hose (not an easy job). Then you need to compact the whole thing with a compactor, and that needs to be done before the concrete dries otherwise you will just smash it all and turn it back into dirt... So you need to mix the sand and concrete and then compact it all in about an hour and a half, which is actually one hell of a rush (for our size lawn anyway). Then once that has dried, you need to get some fairly course gravel and spread that over the top, making sure it is the right shape as the lawn will follow the shape of this gravel. Then you need to compact that really well as well, but this can only be done by making it wet and then walking on it as a compactor will smash the layer of concrete underneath. So you need to spend a lot of time walking on it to compact it. Once you have done all of that, then you can lay out the lawn over the top (bloody heavy stuff!!)