Depends on the country it is in. Countries are free to set their own prices
(within certain boundaries). If it hasn't flown for 10 years, the money is
most probably due to things like Weight and Balance overdue, Setabelts
having reached their 12-year TBO, ASI and altimeter needing their 5-yearly
calibration, leaktest performance, general maintenance, and probably
reregistration (CoR, CoA, ARC), then the export CoA. If all of the above
are applicable, they are roughly 150+250+120+100+whatever is needed at 60
E/hour+450+180 Euro's if all done commercially. Trailer may need
reregistration as well (and maintenance) to get it to port.
The estimate may not be far off, unless work is done by a non-commercial
licensed mechanic (thousands of them around).