Doesn't anyone else think $3000 is too high for 160,000 miles!? Seems high to me
$3000 for a good reliable SSEi is not bad, don't get me wrong. And if you are getting the money from your old car I guess that makes it easier. Hopefully the tranny is in good shape or has been rebuilt already. It would stink to have to sink money into a new tranny in a few thousand miles.
EDIT: Definitely check the tranny fluid. Proper procedure is to check it hot, in idle, after going through all gears for a couple seconds.