I help out at my friend's garage occasionally. They work on domestic cars and trucks, from Model Ts to the muscle car-era almost exclusively. Very rarely anything newer or imported. Needless to say, I don't use metric tools much at all. When I was taking auto tech classes, I used a lot of metric tools -- purchased Snap-on metric combos -- but as numerous people mentioned on here it depends on what you're working on. I have S-K SAE combo wrenches and USA Craftsman sockets. They're great....I recall an old wood shop teacher lived in Canada during the '70s. They used to call Crescent wrenches "metric wrenches" as the country was making the transition from imperial to metric at the time. You can likely put together a quality, USA-made set of mixed SAE wrenches for under $20. Pawnshops around here will sell you any size Proto, Challenger or Blackhawk wrench for 50 cents to $2 at the most. I'd go that route if I were in your position. I've got more time than money.
