Here's the dirty secret of (nearly?) ALL ph meters: they are a huge pain in the ass, eat batteries, need constant calibrating, and rarely last more than a year and a half with daily usage before getting inconsistent and hard to keep accurately calibrated. I hate 'em! Having said that, they are a necessary part of most hydroponics growing.
I make budgets for my growing, and I now add $80 a year, every year, for a new ph meter. If I get more than that out of it, great! Honestly, I get a bit pissy thinking about it - they are the bain of my existence when it comes to growing.
Decent brands: I've always used Oakton meters, and still feel like they are a decent, if not good, brand. However, I wanted to try something different recently, and for me it came down to the HM and the Bluelab. I've heard good things about the non-cheapo Hanna's too, and I'm sure there are others. Both the Bluelab and the HM ph-200 go for about $79 if you look hard enough, and I personally think that's about as low as you want to go for ph meters. Below that it seems quality drops off quite a bit, IMO. Cheap meters don't always have automatic temperature correction either, and that's a must have for me (temps matter in getting an accurate reading and calibration).
To revive one: sometimes you can bring one back from the dead by heating 4.0 calibration solution slightly in microwave (don't boil though) and letting the probe soak in it for 24-48 hours. The heating probably only helps marginally, and may not be necessary. Battery changes sometimes are all that's needed, so be sure you have a battery with some juice left. Also, be aware that calibration solution can go bad, too, and complicate things - make sure you store the calibration solution in cool, dark place, and that it hasn't gone bad (residues, floaties in it, etc).
I sincerely hope this is useful to someone. I'm happy to answer any other questions about PH meters for those who may have them. Hit me up! If I can't answer it, I'll try to steer you toward someone who can.
