Amazon offers Prime members the Philips Sonicare Adaptive Clean Brush Head 3-Pack
, model no. HX9043/64, for $20
with free shipping
. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.48.) That's the lowest price we could find by $17. They purportedly remove about 10 times the plaque of manual brushes.
Of note, this item is expected to ship within one to two months.