You couldn't use an MK8009GAH anyway, as it's 8mm thick (double platter). The Zune 80 uses an 5mm thick drive, I believe (single platter).
RapidRepair is expensive, but they are an option:
Zune 80GB Hard Drive: RapidRepair
Or, you can try eBay. Toshiba offers a 5mm 80GB ZIF drive, model MK8022GAA, but I have no idea if that's ever been tested with the Zune 80 or not. The RapidRepair link mentions that you could get a Toshiba drive, btw.