List price: $44.95 (that's 30% off!)
Used price: $4.50
Buy one from zShops for: $10.00
A few caveats; 1. the review sections aren't the worst. I read through them for a general level of understanding. For any in depth information refer to a textbook. 2. The physical science section is difficult. However, if you can work through the tests it will help..
Used price: $10.97
Collectible price: $16.94