I have three types of Member pins. The first kind you need to ask for at either pin carts or the gift shops at DVC Resorts. To purchase one you will also need to show your DVC Member card.
The next type is one DVC sends to Members, free of charge. They are usually associated with the opening of another DVC Resort or a special event. These are limited edition pins.
The third type is one the DVC sales staff usually have. Sometimes they will either give one to you or trade for one. Stop by the DVC booths and chat with the sales staff and check what pins they have. They don't always have them since they are limited.
As I understand it, there will be 5 DVC pins this year. The general Tinkerbell DVC pin is already out. Then there will be 4 DVC pins, 1 issued each quarter for a specific park. The first will be in February for Animal Kingdom.