.$1500 fixtures$1500 electrical$1500 plumbing$300 window$1200 paint$500 - HVAC (window units) or $3500 HVAC (go all electric here)$500 - Exterior maintenanceNot sure about sheetrock, cabinets, counters, floors, trim, doors, hardware.You have a large oak tree looming over the house.  

We  mow and trim the back yards between tenants.  

Kitchens depending on size and trim level can be 1k or 10k. 5k is safe for my kitchens.

Outside needs some finishing such as window caulk, paint and a few trim pieces.I haven't found any rent info but I'm guessing $400ish / month potential.Owner is offering the house for $18k. 

I usually get satin (for trim)  and semi-gloss for walls.  

I have about 5 years Interior Trim carpentry experience.

You don't need to break the bank buying tons of plants and trees and whatnot; just have him mow it nicely, edge the sidewalks, trim the bushes, and cut out a few flower beds.

Can landscaping be upgraded or trimmed back?

You wouldn't hire an unlicensed HVAC installer, or unlicensed plumber, you certainly couldn't hire a handful of Landscape companies to come out and trim your shrubs and let you decided which company did the best shrub.  

All trim is pine.