You'll need to purchase them at a guest relations booth at one of the parks or DTD. They are not available for purchase at the resorts. Make sure that you have your DVC member card with you when you purchase.
Besides buying the AP at Guest Relations or getting a voucher (good for ordering the Disney Dining Experience) you can also do a will-call purchase. This is good if you are spreading out purchasing APs and don't want to pay the $3 mailing fee for each. You still need to visit Guest Relations to get the AP.
When renewing you get a break, but the it starts on your expiring date. Some will not renew and pay the higher rate because they are not going until a later date. Then have one year from activation date.
I'm sorry. I guess my question wasn't very clear. What I'm wondering is why $315.00 including tax when ordering on the phone as posted by ellenec, but $315.00 plus tax when ordering on line?