Radio Shack replacement of smart phone screens was part of a TV news article on how much original vendors charged to replace the phones vs amount Radio Shack charged to replace the screen - I think it was about $100 to have it done.
Just like replacing a watch battery - its all about having the proper tools to do it.
I did use Internet instructions on how to change the battery in a game boy game - without the proper tool (a soldering gun and some solder) it took a few tries to get the connections and battery taped into place and get the game taped shut - before the game would power up and save.