13-unit listing with multiple building types/ages on two lots

[Jedidiah Link]

I'm looking at a rather unique listing that includes 13 total units - a 1910s multi-story 8-plex, a 1970s ranch 2-plex and 3 stand-alone one bedroom units that were added in the 2000s. These are situated on two adjacent lots in a good neighborhood. They are currently rented out, although the 2-plex is owner-occupied.

I'm not sure how to go about determining a market price though, specifically with regard to the fact that there are so many different types and ages of buildings. Should I price each individual piece as a stand-alone investment and then combine them for a final offer price or are there either hidden challenges or advantages to a sale like this that would either make it harder or easier to manage?

I'd appreciate any thoughts. This is my first post here - long time lurker though.

Jed