The irony for me looking at that chart is that I got a big bag of Red Sea Coral Pro salt for free with my fish tank way back and haven’t used it because I thought the parameters were too aggressive compared to my normal Reef Crystals. If these numbers are to be believed, then I was totally wrong about that. Though I’m pretty sure when people test for themselves they don’t get that high of alk in RC.
Although now like Bruce I’m using Triton method and not needing to do water changes too much. For the first several months I didn’t do any water changes. But I saw some corals not doing well and so I started doing them again and things improved. In fairness, I also wasn’t sending in Triton ICP tests as often as you are supposed to, but I wasn’t seeing any major issues when I did.
So now I’m doing like 15% once every month or 2, more if suggested by the Triton ICP result.
Anyway, all of these salts mentioned are good, and IO is the cheapest, to answer the OP’s question.