maybe i'm weird but i love these drives,   they are 2.5" 10,000 RPM SCA.  but they are about silent,  and so sick fast. and 100% backwards compatible all the way to Mac II / SE.

drive:

http://www.ebay.com/itm/IBM-eServer-xSeries-73-4GB-U320-SCA-Hard-Drive-26K5152-90P1309-TESTED-/171609214694?pt=LH_DefaultDomain_0&hash=item27f4b4cee6



Terminated SCA to 50 pin adaptor:

http://www.ebay.com/itm/Internal-SCSI-Adapter-80-Pin-SCA-to-68-Pin-Female-or-50-Pin-Male-/310390365299?pt=LH_DefaultDomain_0&hash=item4844b51c73



Total cost...  ------------- C H E A P!   

Mounting:

You will have to figure that out on your own, little customization required.