calling home from China
 

Is the most affordable way to buy a local prepaid calling card?

(AT&T prepaid works out to $2.65/min with card purchased at USPS, which at this point is likely my only realistic option.)

IP phone cards (such as those offered by Jitong) are the way to go. Having people call you is also rather easy on the wallet.

If you have MCI as your long distance carrier (or don't mind switching to them), sign up for their International Plus plan. You'll get great international rates and you can call home collect (or use your calling card) at the same rate as it would cost you to call from the US.