Reddit mentions of CyberTech ph-107 Digital pH Meter Tester,Pocket Size PH Meter/Water Quality Tester for Aquariums,Swimming Pools,PH 0-14.0 Measuring Range,0.1PH Resolution,2 Pack Calibration Solution Mixture Included

This is what I use. Works pretty well for mashing and for checking StarSan, and for mead/wine-making.

I bought mine from china for $3 and it works perfectly fine. It looks like this, but not sure if its the same one.

This is really cheap and works well and comes with buffer solution I would just get the whole kit. And then you have a backup meter. Takes a few weeks to ship. LCD Digital PH Meter Tester Water Quality Ph Purity Filter (With calibration buffer solution , screwdriver) https://www.amazon.com/dp/B00ESCZEHK/ref=cm_sw_r_awd_75JGub09TXDZ3

This one comes with an extra pack of solution. CyberTech PHTester PH-107 Digital pH Meter Tester, With 2 Pack of Calibration Solution Mixture Included. https://www.amazon.com/dp/B005KGKCRA/ref=cm_sw_r_awd_B7JGub03YZ51H

Yes. I have done a few batches this year and ran the mash through a food mill on the finest strainer. I then mixed the yield with rice vinegar at a 2:1 ratio with 2 parts mash, 1 part vinegar. I chose rice vinegar for the low flavor profile, but it would be fun to try different vinegars or even try a home made vinegar.

Edit: I had some pretty active mash, so I bought an affordable PH Meter like this one. You want your finished product below 4.0 PH or you could have some explosive results (I learned that the hard way!).