Is this a pouch sling or a wrap style carrier? I can't tell from the pic. Usually Moby is a wrap, but I've never seen one with two types of fabric.
If it is that much, use a *padded* flat rate envelope from the post office (not the cardboard one, padded bubble one--they're free just ask). They're $5.95 free tracking (5.05 printed from paypal) :) And they fit a whole lot. I've squeezed 5-6 toddler outfits in one.
If you can weigh the item beforehand, you can print shipping from paypal in the merchant services tab (if over 13 oz) or by clicking print shipping label by the payment (if under 13 oz--and if buyer includes verified shipping address)