Amazon has the 2-Count Oral-B Indicator Color Collection Manual Toothbrush (Soft) for $3.99. Add 4 to cart (8-count total) to reach $16 - $5 multibuy discount - 5% off with Subscribe & Save (can cancel at any time) = $10 with free shipping on $25+ or with Prime.

Blue indicator bristles fade halfway so you know when to replace your toothbrush.