It would be a total of 2 payments, yes. But shipping may include some of the cost of findings (lobster clasp, phone strap, etc). That part definitely shouldn't be over $1 per charm, though. I just can't charge for it in advance because I don't have access to the charms to see what size of findings to buy.

Of course, there's also the option of just buying the charm alone, if you have the parts to put it together? Then it would only be $8 plus shipping.