$2600 is not too much to ask considering current conditions, but that is good only IF you wanted a Metro. As I understand it, these are downsized engines and unique to themselves.
I would not offer more than $2000 myself (if I was in the market). Our 6/1 CS standard kit (full size) can be purchased for $1990 and accept all the standard Lister parts. Ours come with our own warranty and a solid business behind the sale. We have the full size KOEL 8/1 units priced at $2750.
The market price is being driven by perceived scarcity more than anything else... maybe these are not as scarce as some would assume!
dieselgman