Ref

Notice that you original solution was simplified and used in here. Simplified original solution is in B3:

=REGEXREPLACE(
  CONCATENATE(
    ArrayFormula(
        REPT(
          INT(SPLIT(A2, ",") / Months) & ",",
          Months - MOD(SPLIT(A2, ","), Months)
        )
      & REPT(
          INT(SPLIT(A2, ",") / Months)   1 & ",",
          MOD(SPLIT(A2, ","), Months)
        )
    )
  ),
  ",$",
)