I had a 2nd generation Kindle Fire (HD) which my 2 year old son was using to watch videos and play games. Unfortunately, he dropped it and the screen cracked. We decided to get him a new ruggedized tablet for christmas. Rather than throw my old KF in the garbage, I bought a "C Stock" screen from ifixit and decided to have a go at replacing it.
I'm fairly handy with technology, and the fact that the lcd/digitizer/screen are one part made it pretty simple. In 30 minutes I had the KF apart, and another 30-40 minutes to reassemble (the screws are very small and hard to get into the holes, very frustrating!). I was a bit leery about ordering the C Stock but it only has very minor blemishes, not noticeable unless you are looking for them. And the screen works perfectly. I flashed a standard android OS rather than use the amazon kindle OS and I now have a brand new tablet! The guide provided by ifixit was pretty good, a little confusing at times as to what I was looking at but I got through it fine. If you aren't very good with technology, I would suggest having someone who knows a bit to help you, the ribbon cables can be damaged easily if not careful.
The C Stock screen was perfect for me as I was simply trying to get a few more years usage out of an older, rarely used product. If this is your primary device, you may want to opt for B or even A stock at a little higher cost. While the blemishes are hardly noticeable, they are there, and if it's something that would bother you, then spend a bit more for the better quality.