Is there a reliable way to do the cost approach with an older home made mostly out of wood?  

A fully rehab house would have much less maintenance then a home made "rent ready."

To find your Motivated Sellers, since you said you are low on funds, start by making homemade (or professional) Bandit Signs.

I love the BP team when they pop the hands of the kids reaching for the cookie jar, when the kids are using a 2 legged stool, on 4 phone books, with a homemade teeter totter of a tennis ball under a 2 by 4.  

Many times you are looking for a homemade sign or a dumpster in front of the property or unkempt grass and newspapers filling up.

Homemade always looks homemade.

The theatre also boasts reserved reclining seating and has a walk-through concession including barista bar and homemade NY style pizza by the slice or by the pie.

Chewed up doors, dog feces and urine covering the 2nd floor, and homemade dog kennels in one of the rooms!

I came home and switched my treats from being fresh flowers from the super market and reasonably expensive store bought chocolates to being freshly roasted coffee beans from a local coffee shop down the street and homemade ice cream from a local award winning ice cream shop up the street or freshly baked croissant from the French bakery around the corner.

@Tyler LeeYou'd probably be surprised what a half-hearted amateur sanding, some homemade filler mixed out of Elmer's Glue-All and the sawdust from your floor sanding, and three coats of brush-applied gloss polyurethane will do for most hardwood floors, however heavily scratched.