I don't feel emotionally attached to my house, but it is in a neighborhood we really wanted to be in, close to our jobs, and it was hard to find a place within our price range where we are... plus all the duplexes/triplexes I see online are tiny or super old or in neighborhoods nowhere near where we work...

These people tend to boast about how many units they have thinking that quantity of units seems to matter more than quality of units. 

If you provided your last project as an example and could get them to do the takeoff quantity for the various options they should be able to give you not only costs but also schedule impacts...the cheapest option may take an extra 2 months to construct, so what's your carrying costs on that?  

It’s not that I want to invest elsewhere to make $, I want to explore ways to create affordable housing here by getting creative; ADU condoization, tiny homes, cottage clusters, STR partnerships etc.