Check your evinrude model number and you can find out the shaft length.
Assuming that evinrude is running, with some patience you can probably wait for the right one to pop up and find something. Maybe talk to the shops that sell new outboards. If they know you're looking, they can help their sale if they tell the guy they can sell his old engine for him.
Under 15k you're looking at used. I'd just be looking for something with good maintenance records. You might find a 300 from mid 2010's with all rigging and controls for that price. Maybe even some older twins with good maintenance records, and then you'd have a spare engine to pull parts from. but I'd wait for a full package with controls and rigging so you aren't piecing it together later. You might be replacing the cables anyway because of difference in length, but just depends on the boat it comes off of. You can find the controls etc on ebay if needed.
Watch out for scammer sellers.
