For example, if you were building a custom home for $100/sqft 5 years ago, what might that look like for you today?

I found out by calling their business customer service and getting the skinny from reps.

In my version of all this, I like to land on a rehab once I already have a buyer picked out an prequalified and I know where they want to buy and I can walk a deal I have under contract and do a scope of work and upsell the cabinets,floors etc (manage costs) and the potential buyer is excited about moving into a customized new home instead of a used home. 

Tiny homes can cost more than average size homes after customizations.

Seek out the ones offering the support or lack of it that you're looking for, commission splits and fees will be based on what you want and some brokers will even customize a program to what you want. 

Many companies who build equipment have to prove they are ISO 9001 compliant to sell to some of their customers.

Popular vacation spot for folks in Denver during the summer (Lake McCanaughy). 

I realize my properties are not  really what the typical customer wants.

Their fees are very reasonable and so far their customer service has been great.  

Easy way to verify that is to keep a list of who introduced which customer to the property.