Depends on what you want out of the camera. The gopro cameras are definately a great package and hard to beat for the price. I love the weather proof case, and the mount is pretty good, I've seen them stuck to the rear wing of a formula ford for a 20 minute session without issue (meaning the camera didn't leave the wing, and it was still recording, though the video was useless because of the amount of vibration). But as I mentioned, the mount doesn't have enough articulation, that would probably be my only real gripe with it, that and there isn't a display you can review shots with, oh and on really sunny days it's sometimes hard to tell if your recording or not because the LCD will sunwash like cheap LCD's do. I've had to compromise shots because of the mount, for example it can't be use to get a good forward shot that includes the driver mounted to an NSX back window without throwing away the mount and duct taping the camera to the window. For a miata with the top down though you could get some great shots.
In the same price range I've gotten pretty good video from cheap Aiptek cameras, I had an old setup that used a chasecam lipstick cam running into an Aiptek that had a a/v in which worked really well. The chasecams have a far superior lens and optical sensor, IMO they are worth the money.
If you want good video of the suspension working, or really want to push the extremes of camera angles and shots you'll need to use a lipstick camera like a chasecam.
If you want HD in that price range.
Amazon.com: Aiptek A-HD Pro 1080P High Definition Camcorder (Silver): Camera & Photo
There are thousands of solid state recording devices in that range these days. Like this one.
Amazon.com: Oregon Scientific ATC 2K Action Cam Flash Memory Camcorder: Camera & Photo
Though the gopro is very durable, you should view any camera in this price range as disposable, especially when you concider the environment they need to function in.