you could use the PIC together with L297/298http://www.st.com/stonline/books/pdf/docs/1334.pdf
Then the power consumption will be controlled by the circuit.
You could turn the power off when the stepper reaches it's position
but there are some errors involved if the stepper is in a half step position when
the power is turned off and when the stepper is enabled again it could go to the nearest
full step position - the best way to find out if it is suitable for your application is by experimenting.
If you're only using full step mode then it will be more accurate.