Walmart offers the K'NEX 350-Piece Super Value Tub, model no. 12104, for $10. Shipping adds $2.97, or choose free Site-to-Store.
That's tied with our mention from two weeks ago and the lowest total price we could find for this set by $6. Sales tax is added where applicable.
This kit includes 350 parts and instructions for constructing 20 different models PLUS about 1,000 more options if you are like me and love to create any sort of mechanical toy ;)