Originally Posted by airraptor

The cheap ones record the same RPM as the TNC. I have two TNC's and several cheaper ones. Some of the cheaper ones record highest rpm also. TNC does work better in low light conditions and will pick up the prop from farther away. For the price of the TNC you can buy 3 or 4 or the cheaper ones.
For the cheaper ones I like the Hanger nine one as its pretty small.