Selling it with the case, is probably a better value for the next owner of the phone(unless they already have a case). I wouldn't jail break it, that all depends on the next buyers preferences. You could jail break it, then find a buyer that didn't want the phone to be jail broken, then there you are waiting for someone who wants exactly what you have. Rather the price is right for them is the question. To each there own. Good luck with your sale.