I used a 49 dollar auto meter gauge for two years without any real problems.
Before I figured out the clean air thing .I thought it was working backward. Once I blocked off the top of the valve cover it would read fine . I could see the difference between jet sizes and see it while riding.
This is the A/F gauge . I guess The engine is cold or the choke is on.
http://www.youtube.com/watch?v=33L1972dK4A