If your having to work that hard with your salt system there is something out of balance. You should not be having that much problems. Most often we find the reason people are having a problem is user error due to improper training. Be certain your ph level is at the proper level 7.2 -7.4, keep your CYA at 40ppm, also test your free chlorine and combined (total) chlorine if your combined chlorine is 1ppm or more higher than your free chlorine your pool needs to be shocked.
As far as how much it will cost you in tablets there are several variables it is hard to get a accurate cost on this. You might spend $40 a month while your neighbor spends $20.
What I can tell you is that the problems you are having will still exist with chlorine tablets until you fix the underlying problem.
Oh one more thing you should not be spending $800 plus on replacement cell. What system do you have?