The current price for a Google Glass (explorer edition) is $1500
It is said that the price for the publicly available version will be significantly less than $1500. The release data is set to Q4 2013 ~ Q1 2014.
The best possible Google Glass price would be $200-$300 so people can buy it as an add on to their cellphones.
A very popular opinion is that the price will be $500-$600 by official launch.