The DIY recipe listed here makes it affordable price wise. I think the question would be how much your tank requires. I think it would be a similar question with a established and mature tank be it this product or two part. At some point depending on the corals it gets cost prohibitive and a reactor may be needed.
But it seems this DIY recipe is good. I'm using it on my 210 gallon mixed reef. It is still maturing and only 2 years in but I'm using it. I was using ESV 2 part previously. I love ESV 2 part but I've been slowly switching to Tropic Marin due to their open attitude to our hobby.
I mean they didn't have to provide this - they just did. So I'm really into supporting them with what little I can. Hell, if I find a t-shirt they sell I'll buy that too