Walmart offers the LEGO Ninjago Kai's Fire Mech Play Set, model no. 70500, for $7.57. Opt for in-store pickup to dodge the $4.97 shipping fee. (Amazon charges the same with free shipping for Prime members.) That's tied with our expired mention from four days ago and the lowest price we could find by $3. This set features 102 pieces, including two minifigures with weapons.
Need it by Christmas? Varying by ZIP code, same day in-store pickup is available.