Amazon offers Prime members the Magformers 28-Piece Neon Blacklight Set, model no. 33062, for $22.49 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.32.) That's the lowest total price we could find by $8, although we saw it for $3 less in July. The pieces are made of BPA-free plastic and feature neodymium magnets. A rechargeable blacklight is included.

Update: The price has dropped to $22.05.