For TDS/EC I bought two used HM Digital COM-80's off ebay years ago. They can be calibrated and display EC, PPM and temp. $25
My Apare PH60 is very good and people are happy with the PH20 as well. AC Infinity sells them under their own name for $50 and $80. Apare has a lot to choose from, even Bluetooth versions with phone app.
Apera Instruments pH pen testers, pH meters, handheld pH meters, and benchtop pH meters are designed for professional pH testings in multiple applications such as Hydroponics, water quality testing, food and dairy products.
aperainst.com