A lot of factors would be in that decision. Age, manufacture, type of construction etc. For instance, lets say its fairly new and been a trailer queen... I don't think I would have one if the price was right. However if that boat has been sitting in a slip for god knows how long I would certainly have it checked by a surveyor for water intrusion with a cored hull.
When in doubt always error on the side of caution and that the seller is hiding something. Call me paranoid but it can save your butt in the long run.
The next question is what are you going to do with the information? Any defects to be fixed? Lower the price? Walk away? Banks and insurance may require survey from licensed surveyor. A marina may require one for some types of boats. Spend the money.
I’ve done a bit of research on the expected lifespan of modern 4 strokes. There doesn’t seem to be any consensus - people were throwing out numbers everywhere from 1,500 to 5,000+ hours.
There does seem to be a consensus on what kills outboards (sitting for long periods) versus what maximizes their lifespan (use them, a lot). The motors that last the longest (actual engine hours, not years on the calendar) are the ones that get run hard on a daily basis - the example of pangas in Mexico comes up a lot.
11/12 years, 900 hours, so you’re looking at a motor that was used about 75-80 hours per year. It’s hard to say exactly how many times/year the motor was run without knowing how what the previous owner used the boat for. (Was it used 8 times per year for 10 hour each? 16 times a year for 5 hours each? All trolling? All cruising? Mix of both?)
If it is a cored hull (and from what I understand most are in that size range), you really want the hull (and transom) checked by an expert. Not always easy to detect decontamination or water logging, even with a quality moisture meter.