£95.00 + Vat, full service price list at Servicing | Glasgow and Clyde Outboard Services Outboard Engine Servicing
including what is included.
Buying from a dealer: 3 month warranty minimum + it will have been serviced and guaranteed working but will cost a bit more.
Buying private, cheaper, would always service unless they have recent receipts, could be great or could be a bag of nails.
Oh and for 2k you can buy a new engine with 5 year warranty so I would suggest that 1K for one that is 13-15 years old is not great value.
Last but not least. How do you know its only done 3 hours? I am not saying it has done more but how do you actually know?