Between 9 tanks totaling 2615g in display volume (not counting any qt or sump volumes) on an annual basis that I can easily calculate.
2520 on salt (instant ocean)
1560 on fleece rolls (red sea 1200, clarrisea 5000, bubble magus L)
2000 on frozen fish food (pe mysis, spirulina mysis, ocean plankton, calanus, krill, diy)
600 on dry fish food (various nls buckets, fd krill, fd ocean plankton, seaweed)
1330 on additives (ab+, vitachem, selcon, chaetogro, diy potassium+limewater, 100% glacial acetic acid)
1320 on miscellaneous comsumables (carbon, gfo, biopellets, calcium reactor media)
~350 on 7" 200 micron filtersocks (I reuse these to death so it might be less tbh)
So without counting water+electricity+likely missing items/harder to calculate items(such as testing) I spend about 17690 annually which comes out to almost 1500 a month.
Keep in mind my tanks are not linear in cost (my larger tanks cost way more to feed + do maintenance on than smaller) and I'm very heavy handed with feeding + run 7/9 tanks with a high/very bioload (either large quantities of fish, big fish, or both)