Most cities or counties these days have an online mapping service where you can get information about a particular parcel.

Thank you @Daniel Dietz and @Jay HinrichsDaniel, you've really given me food for thought.

We are buying a parcel with 3 duplexes and 1 fourplex on it and the taxes are about 6k or $1500 per building, or $600 per unit.

I enjoy acting in local stage and film productions, and volunteering for the local food pantry and other nonprofits in my area. 

Rinse and repeat.Just food for thought for you Sir, again welcome to BP

Yes, ask your lender if it would be possible for them to release the second lot,massuming it truly is a separate parcel.  

THEN, arrive at a value for any vacant land, by comparing the price per acre for similar parcels that have sold nearby - needs to be almost identical - same road, zoning, etc.  

List price is $800K (which is pretty typical for a house + outbuildings on sizeable acreage here) but I am fairly sure the sellers would come down, maybe significantly, in order to get this property sold sooner rather than later.Thanks for any help or food for thought you can provide! 

They're listed as the same parcel/ tax information through the appraiser. 

Most land that is listed is overpriced (here in so Cal) as most agents have no clue what it takes to get that parcel ready for building a structure.