Its going to be pricey. There are pH probes for full time use, but they are going to wear out also. So expect to replace them once a year or so.
parasitic pumps can do the dosing of the pH correcting fluids. Also do give it time to adjust, I'd say an hour between dosing and retesting, otherwise you may wind up with a system that is constantly running and over correcting. I'd also give it a dead band, leave alone if its between say, 5.5 and 5.8, outside of then then do the corrections.