You should check in to shipping using PayPal. You can open a free business account. Of course need a printer. But you can save almost 50% on shipping and tracking is included in all the shipping costs. You can ship something like this game, first class, for less than $3. But, if u do go through the PO, this can go media mail, u might be able to save a little bit of money.
I'm sorry, I've been trying to tell everyone about PayPal. I like to offer free shipping, as well, and I used to spend so much going through the Post Office directly. The PO is supposed to let all their customers know about using the internet, to save money. But if you use the USPS website, you can only buy Priority Mail or above