Shop around because the prices fluctuate between sites.

If the answer is the latter, is it possible I would lose the money I think I would save by missing deals while trying to learn and upgrade my site myself? 

I dont really follow any other type of SM so i have to assume there are other sites that folks post on as well when they are upset with their investment and or who ever is running it.

You could take the equity and build a site with smaller cabins in a new area to really maximize your cashflow and efforts. 

If you were bullish on the area and planned on having 3 or 4, then management would make sense, but buying a first property far away only to have some random company manage it, and add on MTR which is not as complicated as STR, but still more uptake is a tall order.

We are still using all the pieces we bought from those sites to this day.

This can be complicated, especially if some unit owners are underwater on their mortgages.

I tried to google but could only find vacantion-like sites with exorbitant prices.- Is there a kind of person who could help me with pre-sale improvements (roughly saying, to tell me what is worth replacing, improving, etc and what is not,1 to make the house more attractive for the buyer)?

Sometimes, keeping things simple is better than making moves that are more complicated.

In 2024, it is 60%.You may also have an option of applying a different method (Section 179) that can give you 100% on some of the cost segregated components, but this has its own drawbacks and complications, so it needs to be discussed with your accountant beforehand.Also, have your accountant estimate your potential tax savings before ordering cost seg.