I talked to Tesla agents about trade-in value of my ICE Jeep. They clearly mentioned, as they do not sell those ICE trade-in's themselves, they will simply turn them to Carmax/vroom.com with no profit. They are just doing this as favor, so some of us can get sales tax reduction. About the appraisal, my sales rep recommended me to take it to either of Carmax/vroom to get an appraisal, which they will match, as he mentioned there is a high possibility that Tesla reps may appraise it lower than carmax. So, i took it to carmax and as expected, they appraised it 3k less than market price (vroom price was much worse). I do not have much time to try craigslist/private sale, as i ordered an inventory which would be delivered in 10days. I did shopped around few other dealers to check if they would offer any higher value than carmax (carmax price + Sales tax saving), but not much. So, I decided to trade-in to Tesla, matching carmax appraisal value.
Carmax appraisal is only valid for 7days. So, if your delivery is later than that, Tesla will ask you to take it back to carmax for re-appraisal (they want valid appraisal by the time you trade-in). As my delivery date was few days past the initial carmax appraisal valid date, I did not want to take chances of re-appraising from carmax, who "may" offer a much lower price than before, I discussed it with my tesla DA and traded-in my ICE vehicle earlier (within the carmax valid date).