Equipment recommendations

I was wondering what some of you would recommend for knock detection systems. I have a knock link g4 now with a light that adapts. I am not sure how accurate that is, do any of you know?

If any of you have any recommendation for one of these that are good that wont break the bank that would be great!

I'm using the Plex knock monitor which is excellent however it's also quite expensive. A lower cost option is the 'Knock Box' from Australia - http://theknockbox.com.au/