Sears offers the Craftsman 11-Piece Standard Short Arm Hex Key Set for $4.66. Choose in-store pickup to dodge the $4.49 shipping fee. That's $7 off list and the lowest price we could find. It includes hex keys in sizes from 0.05" to 3/8".
Of note, Shop Your Way Rewards members will earn a Sears credit with this purchase and may be eligible for additional credits and discounts.