I have replaced many cracked screens. The most recent was my Lumia 920. Not too bad to separate the glass digitizer from the LCD panel. Not sure how the 928 is, but the 920 just requires a bit of heat (you could also use no heat. but then you need more force and pry tools). There is a Youtube video for the whole 920 take apart. Unless there is one for the 928, I would advise against fixing it yourself. I am guessing one is not available yet.
The best advice I can give would be to list you cracked screen phone on ebay and hope to get around $250 for it. Then bite the bullet and buy another one. If you get a used (but still great condition one), that will run you 350-400. So your looking at a hit to your wallet of 100-150 for a working 928. Fixing the thing would cost at least $200. You gotta buy the digitizer (if it is even available yet, and it would be more if you can just buy the glass and have to get the screen attached to it too). Then the torx screw drivers, pry tools, and the adhesive to glue the glass to the screen for replacement.
Good luck.