The reality is the seller never wants to spend the money and the buyer does not have the money- especially for a roof.
CONSUMER ALERT: Never trust the seller to do the proper repairs an a roof, and never trust an ordinary inspector to inform you about the true condition of a roof. Always get an experienced roofer to examine something as important as the roof and its related structures, then pay him for a written report.
True story: I was recently hired by a seller to repair wind damage to a roof. The buyer's inspector had reported missing shingles. I worked for the seller and was told to only do what the inspector said to fix. So I replaced a half bundle of shingles. What it needed was a new roof. It was only about 10 yrs. old, but it was a slapped on mess. There were 2 12ft. dead valleys that were shingled and a chimney that was poorly flashed and probably leaking. I went ahead and caulked the defective plastic boot flashings. First rain after the new owners move in- roof leak. The new owners called me and I explained that I only did what the sellers paid me for. I told them they really needed a new roof.
We do the same as Tinner. Our price is $175.
I always tell them I won't come until after the buyer's insoection and I can see the roof 'punch list'. 99% of house insoection read 'Have roof insoected by qualified roofer'. I get $365.00 for that insoection each time, with oix and a report failing it, or listing necessary repairs and a quote for those. Win-win.
Concerning whole roof replacements, a lot of times they don't even actually do the roof but just use the estimate to negotiate the sale of the home. It's always tough to sell a high dollar contract to a seller. However, new home buyers spend more money on their homes than anyone else within the first year or so of purchasing and often do get the roof done.
Concerning repair work, I usually get the job from both the seller and/or the buyer. The amount of the contract is much lower with repairs and the seller is readily willing to pay this lower amount in order to ensure that the sale of the home goes through without any problems or delays.
I've had calls of that nature for years. Some even asking for a "5 year" shingle. Most of the time the call come from a real estate person looking only for a number . . . no intention of following through on the project. Absent consent to a $100 fee to measure and quote the job, I'm done with them.