I needed to replace one, and they are very expensive compared to a standard 30” model.

In this situation, I also think you would not be able to finance such renovations because all renovation loans will get their values off of "comps" - meaning, comparable properties surrounding the neighborhood. 

Comparing bids would be a good way to do sanity checks on pricing, If they have portfolios they can show you, that will benefit you a lot as well

What if by the time I post there is almost nothing on the market in a comparable location of a comparable quality?

I wouldn't go for a condo, as the HOA fees and restrictions could affect your ability to rent it out, and the resale value will always be lower than a comparable SFR.

Has a ten-year-old roof 3-tab, but the condition is more deteriorated compared to its relatively young age.

Yep, I ALWAYS recommend doing an inspection prior to close. 

Documenting erosion severity, prior concerns, and the contractor's assessment could help support a claim. 2.

You’re are such at advantage compared to when I purchased my first property back in 2005.

Recommend cash for keys here (like you already tried) and getting them to sign a termination of lease.If the lease period ended and they are on month-to-month typically you have leverage (depending on what your lease says, or local laws) to end the lease at the end of the month given prior notification.