I vote for the Apple Store or a 3rd Party Repair person (I’ve even seen kiosks in the mall who do this.)
Just last month I tried the “inexpensive” option of repairing my wife’s cracked screen myself. I bought a new digitizer thingy on ebay for about $15, watched a few videos on youtube showing me how to do it, and went to work. What they don’t mention is just how delicate some of the inside pieces are, and how sticky the glue holding it all together is. I ended up breaking a different, much more important piece in the process of fixing the cheap piece.
Today, several hundred dollars later, my wife loves her new iphone 4s. Doh!