Most compact Macs had a fairly low power budget, especially the post-SE/30 models, so I'd probably reconsider using SCA drives in those, at least any of the >7200RPM models. Modern 7200RPM drives probably actually draw close to the same amount of power as those older, slower drives, but the newer high-speed ones draw considerably more.
I wish there were some cheaper SCSI flash drives available. I really only need 2~4GB of space in the average 68k (or even early PPC) Mac, and $100 for a SCSI2SD is a little high for an accessory for use with a computer that probably didn't cost that much. Somewhere between $25-50 would be much more palatable.