2400sqft Triplex listed & priced as a 800sqft Studio - worth 3X?!

[Stephan Kraus]

Hey BP Community, 

I'm currently looking at a triplex with three individual small houses on one lot with ca 800sqft each, the public records confirms its a multiple dwelling / 3 unit, but only shows the "primary structure" as one studio with 800sqft - The online estimators value the property based off that, and the listing agent recommended that estimate as the asking price. 

Would the actual value not be considered 3x times that? Or what am i missing? There are hardly any comps in the area, a few 3-4plexes but all one structure - how can i properly determine the as-is and after Repair value?

Thanks in advance for your valued opinions!