For 150's - why would someone pay $22,000 for an engine with 400 before TBO when they'll likely have to invest $10,000 in a couple years only to have the plane be worth $25,000???
Should the plane not be priced at $25,000 minus $7700 = $17200 (The $7700 is the required investment to bring it to 0 SMOH. Formula being $10,000 divided by 1800 hours is $5.50 per hour. With 400 hours left...1400 hours times $5.50 of "value" has been lost.)
That's a logical statement - but as you know, markets (any market) are not logical. Emotion plays a huge part in any purchase. For instance, a Palestinian throws a rock at an Israeli, Wall Street gets nervous and suddenly it costs $50 to fill up my car. FUD (fear-uncertainty-doubt) and desire play a big part in any purchase.
So it is with aircraft. A brand-new engine from Continental costs $20,000. In theory, a timed-out Cessna 150 is worth zero since the engine costs more than plane. But, a plane with a timed-out engine can still fly around, so it still has some value. How much? Whatever the buyer and seller are willing to agree to.
Conversely, putting a $20,000 engine into a used Cessna 150 doesn't make it a $40,000 airplane. For $40K, one could get 4-seat 172s or Cherokees. Frankly, whether the engine is zero-time or time-out, it still flies the same. The pilot won't 'feel' $20,000 more performance or utility. So typically, they're unlikely to pay much extra. How much less? Whatever the buyer and seller agree to.
Overall, Cessna 150s seem to hover in the $22,000 price range, because that's where a majority of the population with mid-time engines resides. Have a timed-out engine? It's worth less, but not much less because it still flies around and there are plenty of buyers with money and inexperience to buy such a plane. Have a brand-new engine? It's worth more, but not much because there are plenty of other airplanes with mid-time engines and most pilots don't fly more than 1,000 hours in less than a decade.
