I have read that microSD cards vary by even an order of magnitude in how much power they use in read, write, and sleep states. The sleep state can be ignored with Felix's microSD card breakout since we can cut power to it completely, but does anyone know of any particular SD card models that are low power for read or write?
Even if there was one, unless a family or series of such low power SD cards would be developed, you might find a later buy does not meet the expectations.
So always better to just make your own low power circuit to supply an SD card.
Or use such breakout that was mentioned (//http://#039;t%20properly%20or%20extensively%20documented%20that%20part.).