bumpage there! i have the ultrakit.. it rocks, i have never had any issues. though there is one really weird thing, when the system is powered down and i hookup the blocker by firewire or usb it makes the cpu fan's spin when the blocker is powered on…… other than that, it's great.
If I were trying to save a few dollars (and it sounds like you are) I would look more towards some of the firewire write blockers, perhaps even the ultrakit from digital intelligence or forensic-computers. I'm not sure what the units you mention are selling for, but the ultrakit is about $1200 and comes with bridges for ide, sata, and scsi drives. You also get an extra one in there to attach your storage drive. If you don't think you'll need the SCSI bridge you can put a kit together individually. I'm starting to see SATA more often now, and I would make sure whatever I used was capable of imaging it without using an adapter that may or may not work all the time. You will also need some sort of mobile computer obviously. A notebook or semi portable small form factor. Also in the interest of saving a little money, build it fast enough so that it is also your analysis machine.
If you still want a stand alone imager take a look at digital intelligence's unit. It sells for $800. (digitalintelligence.com)