Welcome to the site.
Edmunds doesn't sell cars - we focus on pricing numbers and offer tons of free buying info. We do have ad partners who can offer online financing quotes. Please see the links under the Car Loans tab.
You can appraise the Sonoma and dial it in for your zip code, color, miles and options. That will tell you what others in your area are paying for similar Sonomas.
I don't know about the clunk. You can get an idea of reliability and specific problems by browsing the Sonoma CarSpace discussions. And the Used Car Buying Checklist will give you some things to think about checking on.