Amazon offers Prime members the Snap Circuits Jr. Electronics Discovery Building Kit, model no. SC-100, for $16.79 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.71.) That's $4 under our mention from four weeks ago and the lowest total price we've seen. (It's a current low by $5.) This circuit-building kit features 100 different potential projects with over 30 snap-together parts.