The flavorizer bars are going to cost between $30 and $100 depending on the model and whether you want stainless. If the body is in good shape I'd offer $40 and settle for $50.
I would, as long as everything looks OK. If they replaced all they said that they did, it should be fine. Be sure to check the connections from the tank to the burners for leaks.
That's a pretty good deal. These are great to fix up. I've rehabbed a few the results of which are posted on the site. Check ebay for aftermarket bars. They're much cheaper.
I emailed him about that grill this morning. I just wanted it for the propane tank. If he answers me, I'll tell him to pass it to you. Just found two tanks for $20.