The house is in pretty good shape and the new buyer is going to build a custom home on the lot so it will get torn down at a cost of around $3k or so.

Okay, what you need is following: - rent roll last 3 years - approved profit & loss of the last 3 years, the last 12 month in detail - property statement (needed maintenance, shape of the units and the building) any violation/permit from the city - the complete unit mix (how many 2 bed, 3 bed and so on) - todays occupancy - market rents for the units (yes or no) - is the property self managed?

You can call the utility company, explain you are considering a purchase, give an address, and see how much info they will give you on trend costs.  

I would not waive it, as that is not helping them shape their behavior (paying rent on time).As an aside, as others have said - $300 seems awfully high.  

Try sprucing it a little bit, try painting the door with another contrasting color and take some of that color to the A-shaped roof border facing the camera in picture on on Zillow.

They were honey maple and a little outdated, but in good shape.

If the tile and backer beneath it is in good shape, have you considered just reglazing the tile to improve the aesthetics?

See if it'll go for one year given your credit, and then keep your credit in good shape.

You can also look at macro-economic trends like population growth, construction activity, rent appreciation, vacancy rate, price trends in this and adjacent neighborhoods and if they are more or less expensive, etc.

I'm very studious/detail-obsessed so I keep a very close eye on design trends myself.