National Geographic has one year subscriptions available through their Facebook offer for just $16. You can do an order for yourself, or gift orders by clicking on the top right hand link.
The offer includes a physical magazine subscription as well as digital.
It says new orders only, but it should work if you are renewing your subscription as well.
Thanks!
says US orders
Subscribe NOW to NATIONAL GEOGRAPHIC magazine
at a special Facebook community price of $12 (U.S. orders)
fine print : This offer is good for Facebook community members in the U.S. & Canada only. New orders only.
Canadian price is C$16.00 and includes GST. Applicable HST will be added to your order.
Sales tax will be added for orders sent to KY (6%) addresses. In the U.S. and Canada, please allow 4-6 weeks for delivery of the first issue.