Amazon has 4-Ct Philips Sonicare Genuine W3 Premium White Replacement Toothbrush Heads (HX9064/65) for $23.74 when you checkout with Subscribe and Save. Shipping is free with Prime or on orders of $25+.
Genuine Philips Sonicare rechargeable electric toothbrush head compatible with all Philips Sonicare snap-on rechargeable toothbrush handles
#1 Recommended power toothbrush brand by Dental Professionals
Removes up to 100% more stains than a manual toothbrush for whiter teeth in just 3 days (in White+ mode)
Up to 10x more plaque removal versus a manual toothbrush
BrushSync mode-pairing & replacement reminders when used with a BrushSync compatible handle (DiamondClean Smart or ProtectiveClean)