I suggest a DIY unit, When I purchaseds my PM25, I found two or three threads on the subject, right here. I used an auto window motor and some 12V stuff I found online. It took me two or three tries, but it works, I can feed from 1/2 inch per minute to 8. Of course I can't remember exactly what I found, but there is stuff out there. I'm using an old (real) battery charger to drive it. I'm pretty sure a power supply from an old computer could handle it.
While I was at it, I added ball baraings on both ends of the X leadscrew. It made a noticable difference hand cranking, can't have hurt the motorized versions.