The Clothes and Armor section of the Marketplace offers equippable clothing (for the Adventurer job) and armor and equipment (for all other jobs). It also offers special outfits (complete equippable packages).
Outfits: Outfits include Astronaut suits, Vintage Diving Suits, Vintage Swimsuits, Hula Suits, and the infamous Hot Dog Suit. Outfits run from $3.50 to $7.50 a piece, but really make you stand out in a crowd - so are worth the cash if you like wearing that awesome suit few people have.
Hats: Hats are hard to find outside of the store. Each Free Realms hat in the store runs from $0.50 for simple hats and monocles, to $3.50 for full head masks like the Dragon Mask or Panda Mask. Once again, these can be well worth your money if you like having outfits that stand out in a crowd.
Pants, Shirts, and Shoes: These clothing items run on a low end ($0.50 to $1.50) for cosmetic pieces designed for the Adventurer class. For items that are designed for crafting or combat jobs, they run from $2.00 to $4.00. Armor pieces are better than any found in-game, and can be used starting at level one - giving you a great advantage if you're leveling. However, these pieces generally won't help you level much faster than the standard rate, and remain mostly cosmetic.
Miscellaneous: This category covers shoulder items for combat jobs (running $3.00 or $3.50), to a few cosmetic items for the adventurer class, which run around $1.00. Like other armor pieces, the shoulders don't really make themselves worth the cash paid except for their unique look; however, the cosmetic items are a great, cheap option to use up extra SC and put a little flare on your character.