I buy Openlog / Blackbox devices from MultiRotorMania because they are as cheap as anywhere else, they ship from the U.S. (sorry overseas customers), and they always come with the correct firmware already flashed to the board. Sparkfun, by comparison, will charge you $25 for the same thing, and you’ll have to figure out how to flash the firmware yourself using Arduino. This can be a problem because I have had some boards arrive that did not have the correct bootloader installed, even though they are supposed to.
I have no relationship to MRM, I’m just a happy customer.