Follow tnimble's approach and use high frequency strips. They are more expensive, but running costs are 30% less, they can be dimmed, you can even have an auto dimmer to maintain a constant light level in the shed, and they start instantly, extending tube life. I have a HF strip over my lathe.
For the spots, LEDS are MUCH more expensive than halogen, but they consume 3W instead of 50W and they don't burn you when you stand too close.