Be careful, there are a lot of cheap and nasty Chinese key bodies on Ebay that require considerable modification to get the two halves to fit together correctly with the PCB etc in them. Whatever you do don't leave the immobiliser chip in the old key body!
Steve
#243 Pearl Black
T4 Location Map
You can use 2nd hand remotes and have new bar codes generated to get it programmed. Just make sure when purchasing that it has the white sticker on the chip otherwise it can not be done.