A quick look at eBay recent sales data seems to indicate the book goes for about $30.00 give or take $10.00. One copy even sold for less than $10 including shipping.
I do not recommend using Noble Knight as a price reference resource. Noble Knight does not have the best reputation among all members of these forums for various reasons including inflated prices. If you want to hear more about this, here's a good place to start:
Noble Knight on EbayThe eBay "sold listings" check box is often your best friend if you want to get a good idea of what something is worth. Of course, you have to factor in condition, shipping costs, and a seller's reputation, but it's a whole lot better than Noble Knight in my opinion.
Truth is worth finding and life is too short to work for money.