Check your 5/10 Red Plum Insert and look for a coupon for $1.50/2 Oral B Toothbrushes.
If you don’t want to search for a deal they have the single pack toothbrushes regularly priced at $.94 at Walmart:
Buy 2 Oral-B Healthy Clean Toothbrushes, 1 ct $0.94, regular price
Use one $1.50/2 – Oral-B Toothbrushes from RP 5/10
Final Price: $0.19 each, when you buy 2