1) Buy one for sale price of $5.99
2) Receive $3 in Register Rewards
3) Use one $1.50 off one Oral-B Pulsar Toothbrush Manufacturer Coupon
4) Total = $5.99 - $1.50 (and $3 Register Rewards) = $4.49
The $3 Register Rewards isn't exactly on your purchase, but if you go to Walgreens a ton, keep it to spend on other great deals!