since nobody answering i have a go. i asssume u referring to the original guitar hero guitar controller.

i know is around rm230 for just the original guitar hero guitar controller. However, i haven't seen them selling standalone. It usually come with the game around rm340. Please correct if i am wrong on the standalone bit. However there are other options:
1. rock band guitar controller - i seen it selling standalone, at about the same price of rm240.
2. unbranded third party controller - u can buy at around rm140.

on the where to buy, not sure, but gamer's hideout is usually the place to go. why don't u call them.