Some products are a waste of money, some are not. As far as salts go, io and RC are almost the same thing made by the same company. RC tends to have a bit higher levels of alk and sometimes ca and mg. if you do weekly water changes, the only other elements your system should need, depending on coral load, is the big three. I have a 50 breeder and the only thing i add is alk, ca, and magnesium to keep things at the levels i want. Everything I add is a DIY mix, so that saves me there. Do to my coral load, i'm dosing about 26ml CA and alk per day, and about 30 ml MG per day. corals are growing like weeds and I'm saving money, so i'm happy. Oh, and I use RC salt with a 5 gallon water change every other week.
tom