Just a tip, if PayPal is used, either to send a PayPal invoice to your buyer of for them to make a PayPal Friends and Family payment to you, email addresses need to be exchanged, this can sometimes be found with the order details >> Show Contact Info.
If not, and you need to ask the buyer for this, make it very, very clear in your eBay messages, as eBay do read these, the reason for these exchanges. Make it clear it's not to be used for an off eBay sale.
@lesliwalke2