All electronics has some very inexpensive (4/$1) pulse transformers that appear to be usable for digital audio transmitter isolation. I have only done preliminary testing, but the transformers I recieved pass a signal of 13MHz, so should be usable for 96kHz transmitters. YMMV. This is much cheaper than the $9/each that Digikey charges, although there may be capacitive coupling that reduces the common-mode rejection to an unacceptable level for some applications.
http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=PXR-3&type=store
http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=PXR-3&type=store