I have one!  It's a MiniDrive case, which is as far as I know the smallest external SCSI case that will fit a 3.5" half-height or 1/3 height drive.  I spray-painted the case black, and it didn't come out that well, but oh well, it works.  The drive inside is a Seagate ST52160N, which is a 1/3-height, 5,400 rpm 2GB drive.  The case has a small PSU so it will only work with 5,400 RPM or slower drives!  It has two standard Centronics connectors on the back and a built-in power cable.  The drive ID switch was cannibalized but the drive inside can be jumpered to whatever ID you want beforehand.
For the drive alone:  $25
With a 3' C-50 to DB-25 SCSI cable:  $30
I'm not sure how much shipping with be, but it is fairly light-weight.  Not more than $10, I'm sure.
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