When these guys got their Ford keys the economy and the dollar were a lot better off. So the price of metal was cheaper plus they caught on to the popularity of these keys for leveling. Your most likely not going to find the Ford keys being sold at the prices that these guys got them for. You can always go to a salvage yard and pull them for cheap but good luck finding them for sale at the same price as when the thread was posted. I was looking for them at the same time of the linked thread and couldn't find them cheaper than 70 a piece.
Unless you pull them yourself your better off buying a kit. The kit keys will be re indexed for your Yukon. The Ford keys work great but they were a cheaper alternative at the time than buying re-indexed keys which were more expensive. That's why they were such a popular mod. Now your going to pay the same price so your better off with the re-indexed keys.
Edit: LOL I didnt read the 2 page! Guess Steven had already gone over this!