Okay, are you swapping or selling, meaning you're looking for other products or cash in return, or you're just willing to send them to someone for postage only, or not even that?
If swapping, post on swap board, too, and say what you'd like in return, whether products or $.
If offering for free, ask those interested to pm you so you can estimate the shipping price. Or, if you want to send them for free, again ask the person interested to pm you, so you can get her mailing address.
First come, first served, is the fairest way to do this.