I have the HD Wing Cam from Hobby King that I bought for $40. It's a pretty good camera. The biggest issue that I have is that the audio and video don't line up, but that doesn't really matter when all you hear is the motor. Also, it can take a second for the camera to adjust to lighting, which can be annoying when you keep aiming the camera up at the sky, and then down do the ground. Apparently you cannot use it as an FPV cam while recording, yet there is a "hack" to force it to do so. If you just want to record stuff, it's a good camera. I'm really glad I bought it. I record most of my flights either with the camera on the plane, or I rubberband it to a baseball cap. It doesn't work very well on a hat because of the wide lens, the plane has to be close to be able to see it. But that's true with any camera that doesn't have a zoom.
If you're just going to record footage, buy something cheap. That way you won't be worried about breaking it. I always velcro my camera to my planes and it's been knocked off a few times but still works like new.