Galaxy S3 glass replacement. Anyone tried it?

Im hoping to get my hands on a galaxy s3 in the coming days which has a crack on the glass panel on the front, the touchscreen works fine as does the phone (apart from an intermittant microphone fault )

My question is: Has anyone bought just the glass from Ebay and fitted it successfully? I'm getting the phone at a very reasonable price and have budgeted for the fact that I may need to replace the whole assembly. But as with everything, if I can get this done a bit cheaper then its money in my pocket Im handy enough doing small complicated work but have never had the opportunity to try something like this.

Does it work out generally?

Are the ebay glass kits generally a good quality? I doubt they are genuine as the only genuine samsung kits ive seen are full assembly kits.