The cheapo cameras worked ok with the problems I listed - rattles from the case, the mounting and battery life. But for £5-15 a time they seemed worth the risk even if they don't work - its not worth sending them back at that price. The quality was OK - see my youtube entries for the shaky ones where I mounted the camera on the headrest using rubber bands.
If you can stretch to it I would go with the phone mount option - most mobiles can take reasonable videos and mountings are widely available together with chargers and memory cards - and blutak is a worldwide product...
Also it is dead easy for casual use, as in you don't have to mount / setup loads of stuff before you film - clip in the phone, set the camera off and drive.
Post back with your videos