Each ‘land’ has its own shopping, appropriate to its particular theme, whether the Old West, Route 66 or a seaside amusement park. There's no shortage of ways to spend on souvenirs, clothing and Disneyana and plenty other non-Disney goods. For collectors, Disney Gallery and Off the Page sell high-end art and collectibles like original sketches and vintage reproduction prints.
Downtown Disney is a triumph of marketing. Once in this open-air pedestrian mall, sandwiched between the two parks and the hotels, it may be hard to extract yourself. There are plenty of opportunities to drop cash in stores (not just Disney stuff either), restaurants and entertainment venues. Apart from the Disney merch, a lot of it is shops you can find elsewhere, but in the moment it's still hard to resist. Most shops here open and close with the parks.