for JMed--TIW is available to Florida Residents, DVC, and (somebody verify), I believe AP holders. You purchase the card at guest relations for $100-125 depending on which group you qualify in. If you decide to buy a card, make sure that you have enough table service planned to get your money's worth! If you don't save at least the cost of the card over the one year membership, it's not worth it. Also if you would normally eat counter service and you're eating table service just because you have the TiW card and you save 20%, you're not actually "saving" money.
I like the convenience of having a rental car. By renting the economy or compact or whatever cheap little thing I can get (usually from Dollar), I can usually make up the cost of having that car in savings on water and breakfast food. Also, I don't eat cooked breakfasts if I can avoid them, so breakfast out is a waste of money for us and an exercise in frustration for me. We stop at Publix on the way to our resort and buy water, granola bars, hard boiled eggs, nuts, etc. Our total shopping bill is usually around $60. 10 days of bottled water = $100-150 for us. 10 days of breakfasts = $150-200 for us, so even with our added rental car expense (usually $150 for 10 days), I can still save $40-140 total. If your traveling party can fit into one of these cheap little cars, you can save even more by venturing offsite for dinner or hitting the Disney store at the outlet mall for souvenirs.
Another way that we save is by asking two simple questions before we buy any souvenirs: 1. Where will we use it/display it in the house? 2. What will be its fate if we decide to pack up and move? If it's not useful and it won't be displayed anywhere and we'd get rid of it if we move, it doesn't come home. (If you could see my dad's "shop" where all of his treasures are stored that he's now face with selling and/or moving, you'd understand why!!) This keeps our souvenir buying mostly limited to pins and the odd shirt or Christmas ornament. Don't get me wrong, I have a TON of Disney stuff in my house, but most of it has been gifted or purchased somewhere other than the parks, often second hand.