Cheaper alternative to go pro?

[Matt]

im after a go pro. But without the price tag. I know you get what you pay for, I've seen some 1080p go pro style cameras for as little as £17. Obviously these are going to be shit and not worth the money at all. 
But is there something cheaper and worth it?

I want it for recording drives, track time, video reviews etc 
So need something with a good mic and able to film in hd/1080 
External memory is a plus