Just announced over on the Playstation Blog, new outfits are coming to LittleBigPlanet on November 6th.
First up, for free and only available 11/6-11/19 are a spacesuit and jack-o-lantern outfit (seen below).
Next up, a set of $0.99 each outfits including a tree frog and gorilla outfit. There will be more to choose from than this, but these are the ones they showed first.
Finally premium outfits for $1.99 each. These include the Solid Snake outfit and Sephiroth outfit.
There are ways to get some together for cheaper:
"Basic SackBoy Costume Bundle - $2.99
At times, we’ll offer four basic costumes at a great price…to make things easier for the ‘must collect everything I see’ personalities
Premium SackBoy Costume Bundle - $5.99
Similar to the Basic SackBoy Costume Bundle, this premium version consists of four premium costumes for the price of three. All characters in premium bundles will revolve around a certain theme…more info to come in the near future."