If you feel you can do better, then it may be time to sell or 1031.It depends on what you plan to do with the money.

We've gone through the Site Plan Approval process with the City, have officially split the lot into three parcels, and are expecting to receive our building permits this week (yay!).

Sounds like you have a good plan. 

Does anyone know how much is the minimum that I can realistically pay for permits, plans, materials, and labor?

I live in California (North Bay region) and I own a SFH here and I am planning to invest out of state.

Recently, I have made the decision to wholeheartedly commit myself to this journey.My current plan is to invest in a multifamily home for house hacking in my local area or perhaps a single-family property with an unattached garage or basement that I can convert into an Additional Dwelling Unit .

Are you planning to BRRR this property, househack it, or flip it? 

A developer did buy it and is now planning on a meat market/gas station at that location. 

The seller has already all the plans approved.

@Dan Heuschele: My plan is to have a long time horizon for my real estate investments.