The rate 1 ETH = 500 GNC means that GreenCoin Token is not cheap at its starting crowdsale price.
While ETH is still not very expensive, it turns out that you can buy 500 GNC-tokens for 1 air. It turns out that 1 GNC-token costs about 25 cents. It seems to me that it is inexpensive. Im probably investing a bit in this GreenCoin project.
You cannot discuss about price of a token without considering the total supply of that. For example A ripple costs only 30 cents. But it's not cheap when you consider the total supply and the total market cap.