Hey Adrian, out of curiosity, and since I didn't see you post it anywhere in this thread: what microcontroller are you using?
If you can tie into the uC's RX/TX lines easily, you could run an OpenLog (microSD card, and 3 pins: 3.3v (I'm assuming you're using 3.3), GND and RX)). Then you can run it at 9600-115200 or whatever, and good up to 16GB. The OpenLog is pretty cheap, and if you're putting hundredthow headers on anyways, you could definitely pop one on with some prototyping jumpers just to see if your uC can keep up.
As always, whether its your builds or your electronics....awesome work dude.