[brk-lnt]

It is a very tough question to answer, as you will rarely find the exact same boat for comparison purposes. I mean beyond the same engine/hull combo, but other things like saltwater boats are likely to have better electronics packages (radar, MFDs, CHIRP, etc.) that a lake boat would likely not have (or really need for the most part).

Saltwater boats would probably also have higher hours, which diminishes the value in terms of depleting "useful lifespan" of the engines, which is not directly related to the saltwater usage, but more of a side-effect.

Thus you might see two similar hull/engine combos where one was a lakeboat and one was a saltwater boat, that might have a 20% price delta, or nearly a 0% price difference, owing to things like hours, electronics, etc.

If you are new to boating, I would probably stay away from any Inboard powered (including I/O) boats. Higher likelihood of hidden issues and unexpected maintenance (particularly for an I/O). Any sort of major engine work or re-power is going to be more expensive and complex. If it is an outboard powered boat, you should be able to value it accordingly, and if the entire outboard, or just the powerhead, needs to be overhauled or replaced, it is a much easier procedure.

Salt exposure will tend to corrode or dull metals a bit more, but for the most part won't have much effect on a FRP hull, so it is mostly a matter of the hit on the engine(s) than the hull, IMO.

I see plenty of 30+ year old boats in FL that have spent all their time in salt water, and have been much more exposed to the elements than a boat in a seasonal area, and they are holding up and running just fine, assuming proper maintenance. If you are handy, and get a good marine survey, there is no reason to NOT buy a saltwater boat if the price is right.