Check that windows open properly 

The tenant also says that I'm harassing her be walking in front of her window.

Does anyone know of a wood window manufacturer that has economical prices?

By doing so you're limiting yourself to a very small window of opportunity within REI, and missing out on all that exists in REI.Second, the answer to your questions of, "...how much to start..." is actually $0. 

The roof has at least been done periodically, but windows are broken, walls are falling down.

It is very common for tenants to leave windows wide open all winter, leave power on and run water without consideration of cost.

Are the windows in good shape?

Do you know any limitations (like to use old Windows version their website supports etc) ?

Once you have decided on a home you will also want a professional home inspector to conduct a more thorough review of the home.Below are the most crucial areas of a home that you should look at, should ask questions about and review critically on your first visit to a home.Interior Windows, doors and door framesCeilingsFlooringFireplaceBasementAtticCabinets and countersExterior Color and qualityPorch and deskMaintenanceGutters and roofFoundationDoors and windowsSurroundings Driveways and walkwaysViews and boundariesBushes, trees and grassNeighboring homes and how they are kept and maintained

@Max T.Yours was 5-5-5 so I thought all haiku rules were out the window :) But good luck with the issue.