Have key but lots chip?

can i buy just a chip for my key for a 1999 206 or do i have to get a key with a chip in it. if i can just get a chip dose anyone no the price and where to get one. i live in nottingham and i a brother in leeds that he said he would pick one up if there anywhere near him. if there a sites on the internet that sells them that will help. i have the card with the codes on . as i cant understand when i went to the car shop they told i have to have a new key as well. i thought as i still have the old key and there note wrong with it. cant they just put a new chip in it. it dose come apart and you can see where the chip was. so if i got a new chip i could put it in or the car shop could. any help will be so gratiful san.