Lars, don't forget germany is closer by road to where most Listers are than the north of scotland.
They do come up on ebay uk now and again, search for "Lister CS" in groups
Business, Office & Industrial > Agriculture/ Farming > Stationary Engines
or
Business, Office & Industrial > Agriculture/ Farming
The other one to check is google for all the farm equipment auction houses, then subscribe to their lists, also Google watch / notification thing.
prestonservices.co.uk often have stuff, but not cheap.
at the moment they have one, running, very nice original condition CS 6/1 complete with fuel tank etc that they themselves removed from the original location, price 550 uk pounds, that's 806 Euro, if you declare to him in writing it is for export and supply a german VAT number and say it is for export then no tax or surcharge on that price.
If you want a lister grab this one, they are getting rarer and more expensive almost by the week
mlb@prestonservices.co.uk