Everyone who is saying a pH meter is overkill - please consider that some of us are colourblind. I, for one, cannot read a pH strip if my life depended on it. The pH's on the strip all look nearly identical to me.
On that note. I had a pH meter up until it took an unexpected departure (aka, I have no clue where it is, but suspect it was purloined). It was great and I used it for cooking (canning, some candies ,and other things are pH sensitive, so are some bread recipes). However, I never used it for beer. And, bummer of it all? I cannot recall what brand I had, which is why I have not bought a new one.
Lately, I have been looking at picking up a new one. From other canners, I have heard great things about the Hanna Checker, it is also fairly cheap. I am fairly certain that is not the one I used, so I have no experience with it.
The biggest trick to using a pH meter is calibrate, calibrate, calibrate. Did I mention, calibrate? Oh and clean it in a sterile solution between uses. Cactus had a point on that, they can be a pain. However, my experience is if it did go off calibration it was only by +/- 0.2. Most of the time that was close enough for what I was doing.
When I had mine, every time I used it I would pull my calibration solution out of the fridge, in its little container, and dip the sterilized pH meter tip into it and calibrate - by this I mean, each day I intended to use it I would calibrate it, I rarely needed to recalibrate unless I used it a lot in one day. I replaced the solution every 18 months - I have heard people say you can keep them indefinitely, but I operated on the theory that it would slowly go off because you are introducing materials in it slowly over time.
So, there's my 2 cents. Let us know what you get and if you like it. I am thinking of picking up a Hanna when I start doing all mash, but will wait until then.
And, did I mention, calibrate, calibrate, clean -- and yes, some of us are colourblind and can't read a pH strip to save our lives. Now, if someone can suggest a colourblind friendly pH strip, I'm all eyes.
And, someone else posted a link to a meter on sale for slightly cheaper than the Hanna Checker (albeit, they look similar) in another thread - here: http://www.homebrewtalk.com/f11/electronic-ph-tester-sale-28-50-a-118245/