I was recently searching for a replacement cable myself. After endless googleing and forums, i found out that small replacement parts like that are not available for the droid yet. Best bet is to sell it for parts, or to buy another broken one (like cracked screen) and do some transplanting.
I know this is an old thread, but if someone new comes across this, then this information I'm providing may just help somebody.
There is a site that sells spare internal parts for phones, I myself ordered a ribbon cable (probably the same type the bloke above me needed) from them and it worked perfectly. Here is the site I got it from:
Hope this helps somebody out there.