Amazon with zhoukoukanglingshangmao has the 8-Pack Generic Betterchoi Oral-B Sensitive Gum Care Replacement Brush Heads (Soft Bristle) for $5.43 with free shipping on $25+ or with Prime (extra 5% off with 5+ items S&S order).

• 4-Pack Generic Oral-B Double Clean Heads for $6.17
• 8-Pack Generic Oral-B Active Charcoal Heads for $8.97
• 6-Pack Generic Sonicare E-Series Sensitive Heads for $14
• 6-Pack Generic Sonicare E-Series Heads for $18
• 8-Pack Generic Sonicare Heads for $14