This is a controversial coin that was banned by the government of India following the controversy surrounding coins of 1 rupee and 2 rupee coins with similar symbols on them. Due to this reason, this coin became rare and the price of this coin shoot up to 600 Rs to 1000 Rs.
Many coin sellers offered me this coin for less than 500 Rs. I also wanted this coin to be in my collection. But one of my coin dealer told me that don't buy this coin from the coin market for extra premium. I asked him what is the reason? He said me that "in 2011, Govt will release the same coin which was minted during 2007 for circulation. That time the market value of the coin will be only just 5 Rs. If you buy this coin now for Rs 600, then you will lose 595 after several years." He gave me a good advice at a right time.
Many existing coin collectors and new coin collectors may not know this fact. So, please don't buy this coin for as of now. It is better idea to wait for some more time to add this coin to your collection.