Hi B, here is the official Galileoscope site associated with IYA 2009.
That has the price at $20, $15 if you buy 100 or more, so not sure if there is another site at the $15 price. Also, price goes up on January 11, 2010 to $30/$24 from the $20/$15.
Oh, looks like Luka posted, too. So, guess this is the right price, prices also went up earlier.