I posted the same topic over on EcoRenovator:
Help me install better garage / shop lighting - EcoRenovator
I had a good suggestion / explination to use my old 4' fixtures with new LED bulbs from ebay (aka China). Apparently you just rip out the old ballasts and wire the LEDs in directly. The bulbs cost about $12/each shipped which is basically the price of new T8 fixtures. They put off more light and are more efficient. A couple of the guys over there are already using these and say they really like them.