There are three main stores on both the Magic and the Wonder. Mickey Mates has your typical souvieners (photo albums, t-shirts, plush toys, pins, postcards, etc.).
Treasure Ketch across the hall has more upscale items (swim suits, polo shirts, luggage, jewelry, collectibles).
There is also a store in the entertainment district that sells duty free liquor and perfume. Can't remember the name on both ships - I think it is Radar Trap on one.
I think at one time there was also an ESPN store, but don't remember seeing that on our last cruises.
You can also buy beauty products up at the spa.