Yikes,
This doesn't sound fishy at all:
"Thank you for all the details, I love it! 
Have you had any other parties interested? I was hoping I could reserve it or something until I am back in town. Can I put down a deposit? I can upfront you a payment immediately if this is cool with you.. Do you have paypal? If not you should set one up at http://www.paypal.com/. Send me an invoice with your paypal for full price of the car] and I will pay it so you know that i'm serious. Okay? "
Won't be doing this, obviously!