I bought a super cheap PH meter off Amazon. Only use it for measuring the ph of my kettle sours but it has worked fine for several years. Don’t measure mash ph or anything else.
Not sure if this is the same one but it looks the same.
ANPETBEST Digital PH Meter, Pen PH Tester 0.01 PH High Accuracy with 2 Standard PH Buffer Powders for Household Drinking, Pool, Soil, Aquarium Water https://www.amazon.com/dp/B08G7Y9219/ref=cm_sw_r_cp_api_glc_fabc_nC.6FbV1QXHQR?_encoding=UTF8&psc=1