It's difficult for a trader to really know the condition of an outboard. Why, also would anyone want to sell a good outboard? (unless of course it is too small and bought in error)
The price I gave was from a trade guide - the retail value for the same engine was £3100 ish. This reflects the fact that the dealer has to find space for it, possibly collect it, take it off the boat, advertise it, check it over, service it and offer a warranty and still hope to make a living. - so, about £1000 mark up for all of that work - he's got to sell a lot of second hand motors to do well.
Secondhand motors just don't seem to be worth much. I find it quite difficult when assessing an insurance claim for what seems like minor damage to a gear case for example. 75hp Mariner, 5 years old, new gearbox and bits about £3000 inc VAT to fix it. The insurance company will write it off and pay out perhaps £1600 to the assured. Unfortunately it is almost impossible for the assured to buy a good condition replacement engine, especially for his £1600 pay out. Makes me feel like a right B*****d giving the bad news
Still, if you are in the market for a S/H engine there can be some bargains out there if you can find them. It works both ways!