Better to go in with a dollar amount and have a little flexibility and don't be afraid to walk out the door if they refuse to budge.
I remember my first new vehicle negotiation in '89 for a brand new Ford Bronco. I spent quite a lot of time in the dealership negotiating only to turn and walk out because they refused to come down that last $1000. I walked into another dealership told them what I was willing to pay, what the other dealership was willing to sell for, 15 minutes later we were signing the papers at my price. It was hard work but I ended up talking them down $5K off the original price. Asking for prices by email is not really the way to go. Get on the phone and talk to them, it gives them more incentive than dealing with an email that could be from some tire kicker wasting their time. Better yet walk in the front door and talk, then you'll really get their attention.
Good Luck