No they don't have access to your email address unless they pay using Paypal then of course they will have whichever email address you use for payments.

Depending what the item is it could be a 'Nigerian Scam' and at best what they are after is an active email address to target later and at worst getting the item without paying a cent.

If it is an item like a camera, phone, laptop etc and it pans out like that follow Go-tazz's advice here