Value of used outboards

I am considering upgrading to a 140 Suzuki 4 stroke.
Will need to sell my 1991 Yamaha 200 2 stroke. Runs very good, will idle all day. Has great compression and low hours according to original owner. It will come with gauges, controls and wire harness.
I have seen prices all over the net from $1,500 to $3,500. What are these engines really worth???

My main reason to upgrade is fuel mileage.
It appears that the 4 stroke will weigh more than my 2 stroke ( 75 lbs.) so I may have to add tabs.

Cbuzz