Amazon offers Prime members the DeWalt 45-Piece Screwdriving Set, model no. DW2166, for $9.99 with free shipping. (Sears charges the same via pickup. Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.) That's the lowest total price we could find by $5, although many retailers charge $20 or more. It includes Phillips, square, slotted, and double-ended bits.

Update: It's now out of stock at Amazon; however, Sears still offers it for $9.99 plus in-store pickup.