Biotin is one example of something you likely won’t consume in your diet and its very cheap at the vitamin shoppe (like $4 per bottle). The calcium/magnesium/zinc solgar bottle is like $12 and last 2-3 months so this is like $4 per month or so.
After awhile you should also examine reducing inflammation and if you are not doing this via food sources I would get cod liver oil. This is a bit more expensive and doesn’t last as long as the above supplements.
Swanson sells cheap vitamins if you are looking at saving some dough.