I've been using a Hanna Red Pen for $45.00 + solutions. I had problems with it at first, but it's been working OK now. Store owner told me that the meter needs to be soaking in the 7.0 solution, up to the line, so the (wick) he called it, stay's moist. Every time I calibrate it, it's pretty close to being accurate. I also double check my readings with API-PH Test kit. Can be bought at any fish store. Reads from 6.0 - 7.8. and seems to be pretty accurate too.
Hope this can help :S5: