I'd go maybe for the price tag above around 20-25,-.Take your pick of the $12-15 options on Amazon. Most I’ve used have been reasonable accurate, and priced where the accidental swim in the aging/mixing tank doesn’t make you cry.
In comparison with professionally calibrated devices my TDS meter is at mostly off by 1-5 points. I can only second that statement for pH-meters, though.Personally, if it doesn't come with calibration reagents it's not very accurate and not worth using.
Provided you have a good sensor and sufficiently high conductivity. Even the best and priciest models need an EC of 75-100µS/cm minimum to correctly work.I assume pH meters are more accurate than trying to read colors in a vial lol.