Amazon has the K’NEX 375 Piece Deluxe Building Set on sale for $11.00 (was $19.99). It includes 375 classic K’Nex pieces and 30 building ideas.
Amazon prices may vary and can change in price without notice. If the above item is not available at the listed price, the deal is dead. Please leave me a comment and let me know so I can mark it as such.