The problem I see around my way is that used motors are priced sky high, and no one will negotiate whether it sells or not, and whether it runs or not.
Set a price, list them, and wait till they sell, it may take a while but sooner or later someone will need them.
The economy is crap and its likely not going to change anytime soon.
Buyers are few and far between and those with money are buying new, those without, seem to have parked their boats and forgot about them.
All last summer the waterways here were pretty devoid of boats and its getting worse every year lately.
Last summer I listed an unknown Mercury lower unit, off something in the 80's or 90's. My guess was it came from a mid 90's V6. I put it on CL $100 higher than all any others listed of the same size. I listed it in 2/2021, it sold 5/2023 for $650 cash as-is. I told the guy I knew nothing about it, or if it worked and told him if it were me, I'd open it up and take a look.
He only needed the case because he ripped the bottom out of his on a rock. He was the only email I got that wasn't some sort of scammer after over 2 years listed. I listed a pair of electric shift OMC 60hp motors that I had for years, both were clean but I had never gone farther than checking compression on them. I put them up for $850 each. I listed them in 2009, they sold in 2018. I got four emails on them in all that time. One sold for $650 to a guy from MI, 900 miles away, the other to a guy a mile up the road here for $500 a month after the first one sold. The ad was up the whole time, I just kept renewing it over and over.
$800 motors here are usually seized or have bad lower units. Good lowers bring more than $800 in the summer.
Motors get cheaper in the winter, but in a few weeks it'll explode and the prices go nuts again.
With new motors over $16k in the 150 range at the dealer, used motors are holding their value because so many flat out can't afford a new one.
The real issue selling anything is that most who have $3,000 to spend on a used motor, likely have the money to spend way more and they sign on the dotted line for a new boat and motor, those who can't are flat broke and don't have $300 let alone $3,000.
Real buyers on CL or FB are few and far between, so are the real ads it seems. I email quite a few people selling various items and maybe 1 in 50 actually responds. When you list something, you get 30 emails right way, all with dumb questions that sooner or later lead to them wanting a phone number, then they're gone. I suspect most of the affordable ads are there for the same reason, to mine for personal info and active phone numbers.
I mess with dirt bikes, mostly vintage bikes, I listed a crap load of holy grail type parts on eBay last summer, all priced to sell, out of 150 ads, I sold three items in 12 months. One took a month to pay, one never paid, and one drove 4 hours to pick up a $50 item to save $15 shipping.