Good Deal or Stay Away?

There is a 2014 SR5 premium with 155k miles for $21k near me. I test drove it today and it runs and drives great with no issues. The only thing I am worried about is that it has been for sale for 145 days on car gurus and not sure as to why. Would this be a red flag to stay away from or a good deal that I should take advantage of? Also would like to hear any advice on getting into 4Runners you have to offer. Thanks!