I bought a cheap probe. It's a bit all over the shop. Sometimes it seems about right. 6.7 for my soil, 7.0 for water, 4.5 for vinegar, 8.5 for bleach disinfectant. Other times the numbers are random. You get what you pay for I suppose.
I use this. It's the most accurate I've used so far.
I used a probe one a few years ago and it wasn't great. I've just done a quick search for probe meters and the closest one I could find in appearance to what I used is this.
Gardman Soil pH Meter
GARDMAN Soil pH Meter The Gardman Soil pH Meter is ideal for checking alkalinity or acidity of soils, allowing you to give the best of care to your plants and crops. A full set of instructions and optimum pH levels guide are included in the kit. Easy to use Great value Helps with optimum plant...



