Getting a renovation estimate

[Allie Schraeder]

I'm looking at buying a 4 unit place with the entire interior gutted; it's just studs, wiring, and lights inside. The exterior was mostly renovated with new siding on all but the back, a new roof, (mostly) new windows and door, new sidewalks. The bones of the house are solid, it's in a decent neighborhood, and it overlooks the river.  A lot of stuff is included but not installed like 4 new forced air furnaces, ductwork, water heaters, PEX, some drywall, and miscellaneous hardware. It needs new decks, siding, and windows on the back, and it needs to be completely plumbed. It needs to be drywalled, painted, trimmed, floored, etc. 

I'm thinking this place is a fantastic deal at $100K, but I have no idea how to estimate the cost of the huge amount of work it would need to be rentable.  Would it be reasonable to bring a contractor with me when I have the house inspected to estimate this stuff?  Should the inspector himself be able to give me a decent estimate?  If the cost of renovating is more than like $75,000, I don't think I'll be able to do this deal at all.