I'm a little late to chime in on this one, but I recently ran into the same issue (dropped my Droid, screen cracked but still worked). Amazon has the Droid touch screen for about $25 w/ free shipping. Looks like there are only a couple left.
Amazon.com: Verizon Motorola Droid A855 Touch Screen Digitizer Replacement Glass Repair Part: Electronics
I ordered it and a cell phone repair shop nearby installed it for $40. So I was able to fix it for $65. Even if I end up getting a replacement by the end of the year, it was worth it for me to get it fixed rather than upgrade too soon. I think I'm going to be using my Droid until Motorola releases a phone running Ice Cream Sandwich.
If Motorola secures the bid for the next Nexus phone, I will be a VERY happy man.