You can buy staffs and shields for Donald and Goofy, but not keyblades for Sora.
You can't buy it in the game, but you can try searching online for them.
Store
EBAY
there are two ultima and ferir weapons
I believe there are 22 keyblades that you can obtain.
You can find Kingdom Hearts in: * Gamestop * Wal-Mart * Best Buy Hope this helps! =)
Kingdom Hearts Re:Chain of Memories is available from amazon for $16.90 new and there is not a Kingdom Hearts III game
You can buy them online :) :P
Moogles
You buy the game :]
The joke weapons are available in kingdom hearts 358/2 days, and give a funny looking weapon look to the character who wields it. Example is vexen's "pot lid" joke weapon in place of his shield.
it should work