Re: 2000 Hours on a Yamaha F115
+1 on getting the engine checked out.
It appears you've had it on a reader if you know it's had 75% usage under 1000 rpm's--at an idle. That's somewhat abnormal.
You should have the lower unit vacuum and pressure professionally tested to make sure the seals are good, and inspect the lower unit grease for water contamination. You'll also want to have the compression tested on the motor.
If it all checks out, hopefully you'll have a jewel for a fair price.