Definitely agree to a price and get it documented. Without it, they could come back at you with a higher price when you go to pick it up. Make sure it is the Out The Door price.
I bought mine sight unseen from a dealership in Washington State. They too wanted a deposit on the credit card. Think I surprised them though. Wanted to put as much as possible on the card ( air miles!
) I was amazed they did ($9500), considering Visa charges the vendors 2 or 3%.
One piece of advice, take your time, search the net, over & over again (OK, two pieces of advice). It took me months to find the car and price I wanted. Don't limit yourself to a local dealer, search nationwide, weigh the cost of shipping/road trip with how much you can save.
Invoice price for a 6M Touring w/Sport & Nav should be around $38K
Good luck