Alternatively, by getting a job and apprenticing for a real business in the field.  

As mentioned on previous posts, there are numerous factors that will give you your answer. 

Ever think on that, why isn't this giant commercial building with this huge open football field of a roof simply throwing up solar?

Plus, the product itself is 17 years old, which is eons in the software field, so it's nice to not be using a startup.Unfortunately I signed up for the free trial and then didn't take notes, and now that I am getting around to the review the features are mostly shut off for me since I canceled several months ago to avoid paying.

Search the BP for ADU appraisals to encounter numerous examples.

Some are posted to the Real Estate Events & Meetups under Real Estate Classifieds on BiggerPockets, Eventbrite, and the numerous investor Facebook pages. 

There are numerous numbers you can look at but it really depends on what your investing goals are for. 

I have no experience in this field aside from the books and videos I've been watching (Drinking from a fire hose).

It is a long football field shape lot, with a small single family rental home on it.   

We purchased it for the purpose of rezoning to commercial and expand our existing business model (workspace rental for people in the creative field).