Amazon offers Prime members LEGO Star Wars: The Visual Dictionary Updated and Expanded for $10 with free shipping. (Non-members can spend $35 to bag free shipping; otherwise, shipping adds $4.98.) That's the lowest total price we could find by $4. It features 144 pages of illustrated and diagramed LEGO Star Wars characters and contraptions.
Update: Note that this item is temporarily out of stock but can still be ordered for delivery when available.