TIPS
I'd always by micro sd cards that are class 10 and from Kingston because on many of their products they offer lifetime guarantee
Never buy cards from randoms on eBay / Amazon as their are too many fake cards out there pretending to be fast high capacity Sandisk ones for example from dodgy sellers. Always go for reputable sellers, it's not worth the agro.
Great forum
http://forum.dashcamtalk.com (though it seems to be down right now)