My garage is 24x32 with a 12 foot ceiling, and I have four 6' HD flourescent lights and they are great. They'll light off instantly even at 20-30 degrees.
HO or high output flourescent tubes are used in signs for cold temp lighting and longevity, if you shop is cold and you would be looking at alot of cold starts these are a good bet.
I know of a couple guys who got old gas station sign boxes and hung them.
