I would wait and buy it on site at any guest relations.
From WDWinfo.com ~
Tables in Wonderland (TIW), formerly the Disney Dining Experience, offers Florida Residents and Annual Passholders 20% off of all food and beverage purchases at the participating Disney restaurants. It is a membership program with annual fees.
The price is $75.00 for an Annual Passholder, $50.00 for a second card. For a Florida Resident who is not an Annual/Seasonal Passholder, the cost is $100.00. It is $50.00 for lost/replacement cards.
The TIW Card can be purchased at any Disney Guest Services location. Annual Passholders and/or Florida Residents need to provide proof of eligibility. Note that TIW membership requires that you be age 21 or older.
If you are dining at a Disney Resort with valet parking and are using your TIW card, they will waive the valet parking fee. Be sure to advise the attendant and show your member card.
NOTE: Your check will have an 18% gratuity added regardless of party size.
The TIW discount is not available on holidays including New Years Eve, Year Years Day, Easter, Mothers Day, Fourth of July, Thanksgiving, Christmas Eve and Christmas Day. Certain restrictions may be applicable. Participation is subject to change. To view Disney World Restaurant menus click here.
Tables in Wonderland phone #: 407-566-5858