Hi Isaac:
Downtown Disney is an awesome shopping, dining and entertainment complex. It's divided into 3 sections—Downtown Disney West Side, Downtown Disney Marketplace and Pleasure Island, with most shopping concentrated in the Downtown Disney Marketplace area.
Although stores are always changing, check out
this link for a list of current stores located at Downtown Disney. My favorite is the extremely large World of Disney store, which is like a mini-department store, filled with clothes, collectables, food, candy, costumes, crafts, and more. My boys also insist we check out the Lego store and Goofy's Candy Co. If you peruse the list of stores, you'll also find boutiques, various clothing stores, create-your-own tee shirts, Christmas store, bath shop, art gallery, and more.
If you get hungry, there are no shortage of restaurants to visit, such as Raglan Road Irish Pub and restaurant, Wolfgang Puck Café, Earl of Sandwich, T-Rex Restaurant, Rainforest Café, Planet Hollywood, and various other food-service locations. Other entertainment options at Downtown Disney (each with admission fees) are a movie theatre, DisneyQuest arcade, and Characters in Flight (a ride in a basketed tethered balloon that takes you 400-feet above for 360-degree spectacular view).
To see if you can avoid taxi fare to a mall (and spending commuting time while on vacation), I would check out Downtown Disney to see if it fulfills your shopping needs before you head out to a mall. If you venture out, you can check out the Orlando Premium outlets (premiumoutlets.com/orlando/) that's about a 10 minute drive away (Mears Transportation currently estimates the fare at about $18.) There's also a nice mall, Mall at Millenia (mallatmillenia.com), about 25 minutes away that should cost about $40 or so in taxi fare.
Enjoy your vacation.