I was looking into a Lexus ISF for a new car. Well not new, but a used ISF thats fairly new with low milage. How much $$$ would it cost if I wanted to trade in a 2007 Lexus IS250? It is silver, fully loaded, and 31,500 miles on it. We payed $28,000 for it. So what I'm basically asking is...my 2007 Lexus IS250 + how much money = Lexus ISF? Thanks!