Cool, note that for the drives that don't come automatically with audio firmware, you have to flash the drive. This is easy enough to do, but requires you install the drive and run a DOS utility to flash the eeprom, and there are links on that page to all the firmware. It's a one shot affair too, and it does something to the SCSI ID numbers after that. I've done it though without issue on two drives. I do have a spare audio capable drive if you need it. (It's been sitting on a shelf since I flashed it about 5 years ago.)
The link I posted has a listing of drives that will work, and a pretty good explanation of HOWTO, and how the drive will identify on bootup if the firmware is correct. Also, dat2wav wants to run in a Win9x DOS window. I've not tried to run it from DOS itself. So you'll need a box w/ Win 98.
Ebay prices for drives are all over the map, with some vendors wanting 1990 MSRP pricing....Although one guy was selling one along with VDAT (which is like dat2wav but with a GUI front end, but the site was on compuserve Germany and is gone now -- I haven't tried to find the programmer, as he wanted something like 50 or 100 euros for it and dat2wav worked fine for what I was doing.)
FreeGeek is a possibility, but they don't seem to keep tape drives for the thrift store and they don't take requests. I've found one there in all these years, and it was broken. The only issue is the drives are all getting long int the tooth. I'll keep on the lookout though.
Also, the 2500 is available too.
Don