Amazon offers Prime members the ZOOB BuilderZ S.T.E.M. Challenge Set for $22 $19.79 with free shipping. That's the lowest price we could find by $6, although we saw it for $5 less during Black Friday week. It includes 175 ZOOB pieces, four wheels, a ball, 24 rubber bands, two foam play pads, string, challenge cards, and five instruction guides for building a catapult, zip line, trampoline, and more.