I'm selling a working HKT-0120 Dreamcast Development Box with an internal HD (the one in the middle in the above picture). It's a Set 5.24 (latest).
For more information on this item, you can visit this page:
http://segakatana.com/hardware.php?cat=dcdev&id=hkt01
I'm looking at $650 USD and I accept paypal.
Feel free to send a PM if you're interested!
Cheers