Re: How to factor engine rebuild for pricing?
I'd say: it depends. A new reman/rebuilt engine is worth SOMETHING in most used boats because you are getting above average condition for the powerplant. Sure, a boat doesn't sell as well (or at all in some cases) with a non-running engine, but would you pay more for the same boat with an engine having 750hours, or 30 hours? Again, it's likely worth something, even if it's an extra $250-500 on a $6K boat. I'd say 10% or less increase in price depending on factors like what was replaced, who did it, receipts, etc.
The other part of "it depends" is related to the boat type itself. If this is an offshore powerboat with two rebuilt SC'd 8.1L engines, you are going to pay more than the guy with 300hrs on the engines. Of course none of this helps out the hours on the outdrive, but still, a rebuilt/reman engine is worth something.
My personal example: I just installed a reman engine last year, new everything that bolts onto the long block (carb/dizzy/wires/coil/flame arrestor/fuel lines/EVERYTHING). You're going to tell me than I can't command an extra couple hundred dollars for that over the same boat with original 1976-vintage equipment? Will I get back the few grand that I put in it? Of course not, it would be insane to think so, but to say I can't ask a few hundred more for having everything new between the doghouse and the gimbal ring is silly. Just my .02.