Round tube aluminum Treks - with Easton or Alcoa tubing - are nice compliant rides. I always thought Trek went backwards when they introduced the triangular downtube Alpha Aluminum tubing in the late 90's. Those frames were much stiffer and less compliant, as they chased the racer segment of the market. All of a sudden, not so comfortable frames unless you're a racer.
But these days, down tube shifter bikes like this one are having a really hard time. So I wouldn't be buying to flip right now, only to ride. Even if you had all the consumables on hand and was able to rebuild it for nothing, it would still have a hard time selling compared to recent prices.
People are getting rid of their pandemic bike purchases at firesale prices, which drives down the rest of the market to the point where it's really not a go anymore. At least that what I'm seeing in the local market.