This is one I've been using with reasonable confidence.... it at least shows accurate variances between my tanks and agrees with my municipal water results.... Got it off our local e-bay for around $75, so hopefully it should give a reasonable indication.
I had one given to me when I bought a fish tank on eBay. Looks a bit like the one in the first post but red, needs calibrating as my tank is 7ph and the meter reads 5.5ph
Personally I wouldn't bother, I don't see the point, you need to calibrate these things frequently, there's nothing wrong with liquid pH reagents, they're as accurate and precise as we require them to be.