Boxnovo via Amazon offers the Aroccom Electric Toothbrush Replacement Head for Braun Oral-B 8-Pack for $10.06. Coupon code “AROCCOMP” cuts it to $6.35. Plus, Prime members bag free shipping. (If you buy via Subscribe & Save and apply the coupon, your final price comes to $5.85.) They’re compatible with a wide range of Braun Oral-B toothbrushes. See the product page for a complete list.
Boxnovo via Amazon also offers an alternate 8-Pack for $6.95 via the same code. (If you buy via Subscribe & Save and apply the coupon, your final price on this one comes to $6.45.)