Same here, there is always a few used ones at the consignment auctions. Even the real Kubotas and Yanmars dont bring much, anything else brings scrap unless brand new in box and they have a hard time getting $2-300. I laugh when I see one on fleabay for $2-3000
Why? Here is what you will hear from those who brought them in and used them which around these parts, the Amish
They were Noisy, Short lived, Hard to start and no parts. That was enough but what sealed the fate of them AND Lister/Petters and both the CS and Listeroids plus all other other high quality small diesel engines was the one two punch of $4 diesel fuel and the arrival of $85 Honda clones. There is practically zero diesels under 25HP in operation any more around here. All being replaced by Hondas and the Lifan clones. Those that are running small diesels for chore engines is because they are running some sort of waste oil for fuel but when the engine needs repairs they dump the entire program for a Honda or clone.
Other communities have stuck a little more with slow speed diesels depending on the local dealers and service levels but around here they are mostly just curios and relics with the only one bringing any money at all is the occasional CS that comes up for sale.