AJ, at what price point does one cross beyond the "toy" threshold for pH meters?
That's not an easy question. Obviously I can sell you an MW101 for $300 (if you are foolish enough to pay it) but that doesn't make the meter a professional meter. After years of buying instrumentation of various types for a diversity of purposes one develops a sense of where the thresholds lie. Specs alone are no longer adequate as the toys have specs identical to the industrial quality meters. What they don't tell you is what their test conditions are when they measure '0.01 accuracy'. I take that to mean that if you do a fresh cal and then return the probe to one of the buffers and take a series of measurements over some reasonable period of time such as half an out that the measurements will exhibit 1 sigma dispersion of 0.01 about the buffer's published value at the temperature which will have been held constant for calibration and the test. I have, in all the specs I have ever looked at, only seen it confirmed once that this is indeed what the accuracy spec for that meter (the Hach Pocket Pro +) was based on. It is interesting that Hach does not give that assurance in the specs for any of their other meters. Think about the same question applied to toy microscopes or telescopes.
One might hope to gain some insight by looking at who sells the meter to whom. If the meter is found in the Cole Parmer catalogue, for example, one might expect that it is not a toy. But they sell lots of the pocket tester type meters (which I have been calling toys) as there are industrial applications for which they are adequate. You can look at the brands you find listed in such a catalogue: Hach, Oakton, Thermo/Orion, YSI and get an idea from that as to which are the 'better' brands. Another thought is to keep your eyes open whenever you are in a brewery to see whose meters they are using.
The other problem with price is that once the electronics get to a certain level (i.e. digital with ATC) marginal price often depends on features such as multiple channels, ability to accept other sensors (ORP, ISE, conductivity, DO), computer interface...) that you may not need. Paying $1000 for a meter that does some of these things is a waste of money if you don't need them.
It gets even harder with electrodes. You can look at electrode descriptions and find things like 'double junction', 'renewable junction', 'refillable' etc and conclude, that since these features add cost, that they must be worth having. And indeed they are. Refillability, for example, is worthless to you if you use the electrode so seldom that you wouldn't consume the gel in a non-refillable electrode. Ten years ago I would absolutely recommend renewable, double junction electrodes for brewing because of protein. With modern more conventional junctions neither of these seem to be so important. We note with interest that electrode life is never specified.
Do you have any specific recommendations?
This is tough for some of the reasons set out above. I can't say whether a mid priced ($400) YSI meter is a good buy or not as I have never had my hands on one (but I have seen them in breweries). I'm not Consumers Reports for pH meters. I can make comments based on what I have seen here and else where in Reviews but even that may not be up to date and the MW101 owners get upset. I can also comment, again with respect to that meter, that I would be remiss in recommending an analog meter when the same company makes a digital meter for nearly the same price.
Would you mind sharing what make/model you use and/or prefer?
I use an Hach HQ40d meter in the brewery and a Hach Sension benchtop in the lab.
I also have a little box that plugs into my iPhone that I bought from Hach though it is made by someone else.
I would not recommend any of these to anyone here. Not because they aren't good meters but because you would be paying for features you don't use. When I do stuff like run titration curves on malts that are going to be published in Palmer/Kaminsky's book the data has to be as accurate as I can get it. The lab meter I use takes a reading every 10 seconds or so and those readings go straight to a computer where they are ghraphically displayed so I can clearly see when equilibria are reached, average readings, do calibrations by moving cursors around on the screen etc. If you need to do that sort of thing then I enthusiastically recommend these meters. They also use an indestructible, it seems, renewable junction electrode that just won't die.
I have read (ravenously) your advice throughout this site, and it is abundantly clear that you believe a good pH meter is a prudent investment.
It is but the question of what to buy is almost as broad as 'What car should I buy?'