Unfortunately you pay for what get, more money means better picture quality, build, more features, more mounting options, etc.
I started of with the cheap
EBay cameras and the were fine, fairly narrow viewing angle and cars have to fairly close in front of you for reading registration plates. Build quality was poor and eventually they did not recharge properly, but for for such a small amount not bad value for money.
You may develop a problem that you want better picture quality then you start buying more expensive stuff, like me
. I have a ContourHD 1080p, excellent camera for the money, used it every commuting day for the past five months and absolutely no problems. With the release of the new ContourHD GPS the 1080p has start to come down in price. I also have a DogCamSport h720 mini DVR system which is a quality bit of kit but not as good as the ContourHD, although it knocks the pants of the ContourHD on unlit roads at night.
There recording times are only limited by the number of spare memory cards and spare batteries you have.