Walmart offers the Hyper Tough 18-Piece Combination Wrench Set for $10. Opt for in-store pickup to avoid the $5.99 shipping charge. That's $6 off and the best price we could find. It includes nine wrenches of metric sizes 6mm to 18mm and SAE sizes 1/4" to 3/4".
Beware these cash-guzzling missteps when you stop at any gas station.