Amazon has the Bosch 5/16" x 4-1/2" Fractional Jobber Black Oxide Drill Bit (BL2147) for $0.67 with free shipping on $35+ or with Prime. Sizes 13/64" (BL2140) , 7/32" (BL2141) , 9/32" (BL2145) , 15/64" (BL2142) , 19/64" (BL2146) and 17/164" (BL2144) are also on sale for the same price.