I have the $30 set and the more expensive jonell pitch gauges.... I was not as impressed with the jonell as I expected. Yes they are very easy to use but they also have a lot of play in them, more so then expected.
The down side to the cheaper set is you will have problems fitting the tabs in the ball on older drill bits, or drill bits that have been resharpened. It takes a little more work to do with the cheaper one in the conditions mentioned above. I actually trust the cheaper set more.
I can not say I think the jonell are more accurate.