Cripe Distributing via eBay offers the Irwin 30-Piece Drive Set, model no. 1885554, for $11 plus $6.25 for shipping. That's the lowest total price we could find by a buck. It includes a molded plastic case and various bits that fit all 3/8" and 1/2" corded and cordless drills.
Walmart offers the Irwin 30-Piece Screwdriver Set with Bonus Tape Measure, model no. 1904305, for $14.98 with free shipping. That's the lowest total price we could find by $5. It includes 21 contractor-grade insert bits, four double-end power bits, four magnetic nut setters, and a tape measure.