Do you have a local appliance repairman? I bought my last washer from a man who refurbishes and repairs older appliances.......it worked for 14 years, and saved me a lot of money. That could be an option.I wouldn't get a used one. I do a LOT of wash, I want something that will last.
The stacking set we have now (washer is broken; dryer works, but not very well) is full size...we bought it about 9-10 years ago. The new ones we've seen in stores are all too deep to fit in the utility closet (and close the door...it faces our dining room, so I really need the door to be able to close).
We will most likely have to special order a set. Gotta love paying extra for a smaller appliance (happened to us with our stove: it was a few inches narrower than standard, but we ended up literally paying twice as much).