DS14 bought the black adult size; DD12 bought the gold 50th anniv. ones, and DD9 bought the pink child size. They put the name on for free. The gold anniv. ones were the most expensive - $9.95. The others cost less. For all three with tax it was about $32. We bought ours at the place in Toontown where they have three rooms of characters. There are quite a few places where you can buy ears, but a lot less that have the old sewing machines.
Not a lot of people buy the mouse ears anymore, so our kids got lots of complements and attention from CMs whereever they wore them. (Believe it or not, it was the 14 year old's idea to get the ears!)