When you use paypal on something else, like buying from somebody on a forum, you put the email address for the recipient, mark goods, how much money you are sending them, and there's a comment box to put a note to the person you are buying from.
I've had paypal for about 4 years, and have only used it 4 times or so (all in the past couple months) for anything like ebay or an online store.
I'll just make it easy and send an email through my email and do a pay pal seperatly.
EDIT: THese would be my first Geocoin in my collection, so I don't have anything to trade for the Copper ones.