They did poor due diligence and a poor business model.  

Your expertise would be greatly appreciated!

The best and most appropriate way to get a value, in my opinion, would be to use a discounted cash flow model.  

very true, stay in the area you have expertise. 

I dont know your business model exactly but I assume you collect some referral fee from the supplier?

Self storage based on aself service model can be done while your golfing, out fishing, ortraveling.

We are everyday approaching a European model where people own less and less of both land and buildings. 

Some high-end STR's (like in Joshua Tree) do use professional models, but for your market and property type, I’d suggest removing personal photos and focusing on the space itself, so guests can imagine themselves there, which is really what you want.You also have 81 photos, that’s too many.

Building a reputation as an investor who helps homeowners can lead to future referrals and a sustainable business model.

The very fact that they are engaging in the business model of illegal brokerage is all you need to know.