Walmart offers the LEGO Ninjago NinjaCopter Play Set, model no. 70724, for $41.99. (Amazon has it for the same price.) Opt for in-store pickup to avoid the $4.97 shipping fee. That's the lowest total price we could find by $4, outside the price below. (For further comparison, we saw it for $6 less in May.) In addition to the NinjaCopter, it includes four minifigures.

A close price: Kmart offers it for $43.32 via in-store pickup.