Walmart offers the K'NEX 375-Piece Deluxe Value Tub, model no. 13597, for $10. (Amazon charges the same for Prime members.) Choose in-store pickup to avoid the $4.97 shipping charge. That's $8 off and tied with our mention from four weeks ago as the lowest total price we could find. This set includes 375 pieces and ideas to build 30 models, including a truck, helicopter, and dune buggy.
Walmart offers the K'Nex Tinkertoy Big Top Building Set, model no. 56538, for $27.97. (Amazon charges the same for Prime members.) Choose Site-to-Store pickup to dodge the $4.97 shipping charge. That's the lowest price we could find by $13. Among the 188 pieces are spools, rods, flags, washers, and end caps.