I do direct booking through the Houfy website, taking credit card payment by Square. 

I've seen estimates of $200 to $400 per square foot for SoCal with $700 sq ft for something higher end and building up a hill and but possibly higher for San Francisco Bay Area (lhigher labor costs, etc.).  

The new facility, dubbed "Arsenal 1," will encompass 5 million square feet and is expected to start manufacturing operations by July 2026.

Nonetheless if you can build a 7 plex for $700K (in my area, things are getting built for $200-300 a square foot), it definitely seems like a profitable endeavor. 

Purchase price: $5,000,000 Cash invested: $1,450,000 Complete combination and gut of two lofts side by side resulting in a 4,000 square foot home.

But it wa a decent gig for people until a year or two ago.

Dave Meyer and Henry Washington shared their opinions on purchasing a deal sight-unseen in yesterday's episode of the BiggerPockets Real Estate Podcast: How to Buy Multiple Rental Properties a Year (Is It Possible?)

I probably can get 1500-1800 per month rent for a 3 bedroom, 2 bath (appx 1200 square feet) and can build for 174,500.

I just hired an architect to design and plans submit for ADU in my 8 multi unit to use the tuck under parking.Some people say do not try to be the general contractor as it will take way more time, costly mistakes and will be nearly impossible to manage with current work. best to hire a company that will do it all and cost about $250 per square foot.

In the meantime I would touch base with lenders and get the financing squared away.