Amazon offers Prime members the Bosch Daredevil 13-Piece Spade Drill Bit Set
, model no. DSB5013P, for $19.58
. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $6.42.) That's the lowest total price we could find by $8. It includes 13 spade bits from 1/4" to 1-1/2".
Note that it ships in two to four weeks.