With orders of $25 or more, Vanity Planet via Amazon offers Prime members the Dazzlepro Travel Sonic Toothbrush
in White, model no. DAZ-7020, for $8.99
with free shipping
. (Non-members can spend $35 to bag free shipping.) That's the lowest total price we could find by $10. It features two brushing modes and includes a cover.
Note that it's part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more.