Do you have a local B&N store?
Yes I too had a problem getting a replacement for my son's Nook. The USB cable has a know flaw causing it to break and that BN as I was told by Cust. Svs, and they are trying to remedy the issue, but not if your Nook is out of warranty... ... My Cust. Svs rep. said that they are indeed out of the cable, and they are sooooo far back-ordered that they could not give me an delivery date. Finally, his supv. who confirmed everything just sent out a gift card to get the USB cable at a BN retail store.
I had an issue with my cable as well just a few months back. The plastic has actually broken apart and wires were exposed so that it would no longer charge (I even tried electrical tape doing all I could to salvage the thing rather than pay $25 if I didn't have to). I brought the cable in to my local B&N, the Nook expert there told me it was a common thing and handed me a new cable - no questions asked!
I asked him why the cable would degrade like that as my cable sits in my nightstand unless I plug in my Nook to charge. It does not get battered around at all. He said that even though B&N claim you can use your Nook even when charging, that this is what causes the cables to go. If you use your Nook while charging, the cable gets heated up quite a bit and that is what is causing the issue. He suggests that you don't use the Nook while charging at all in order to save the cable from being destroyed.
Also, I do feel I have to mention that I am not a regular to the B&N store so it's not like the Nook expert was "one of my buds". Just very helpful!