Mike over at ReadyMade spotted this $5 on a Dewalt 6-piece Spade bit set at Amazon. The bits are designed with cutting spurs for hole-finishing and have a hanging hole for wire pulling.
Less than a buck a bit is almost throw-away money. To avoid shipping costing you more than your savings, try adding the bit set to a larger order you have coming to you already. Hey, anything that helps save green, right?