PH up and down is worth it. It's precise and well tested etc.

I bought a Hanna GroCheck continuous meter. It's like $120 at some pretty big online hydro stores (bghydro.com). I keep it in my water 100% of the time. I'm lazy like that

Also when you get a meter, take note of which calibration fluid you'll need for the EC/TDS and buy some. Buy some PH fluids also.