The big thing (for me) is the hundredth decimal point. You're shooting for 5.4 to 5.6. 5.5 = 5.45 to 5.54 depending on the rounding method they use. I have/had the super cheap Milwaukee. 1) It just died after a few months, but it was $15 so I am not overly concerned. 2) It always drove me nuts to get a 5.4, 5.5, 5.6. Granted, those were acceptable answers. Give me a 5.4 or a 5.6 and I'm all bent of shape. I know I was 5.35 to 5.64, but how close was it. If I came it at 5.5, how close was I to the 5.46 the spreadsheet I use predicted? It drove me crazy. I would also get a meter that has a 2 point calibration minimum. Single point meters calibrate at 7. Dual point will use 4 as the low point, which gives you better accuracy down where you are measuring. Myself I just got a lab grade meter of ebay that is likely overkill, but that is me and there is nothing I can do about it. From my research, however, either go with the above advice of a decent disposable, or at least look for separate temp and ph probes, it reduces the cost of the replacement ph sensor down the road.
And to anser your question, +/- 0.2 isn't so good when you are targeting a 0.2 range.