There are tons of stuff to choose from at WDW... however, they do tend to be pricey. I personally have come home with a tye-dyed T-shirt, a flashing Mickey ears hat, a Singing Birthday Pooh Bear (got this one on my Birthday), and a small variety of Disney Pins.
But I have also gotten the least expensive souvenirs around to hand out to co-workers and friends... Pressed Pennies! There are tons of these machines spread out all over the WORLD... and best of all they only cost .51!! so you can get a lot of them. They also have pressed quarters...
All in all, it depends on your taste and who you are buying it for.