@Genevieve P. Thank you so much! That worked perfectly!

For everyone's reference, here is how my formula turned out to allow for non-numeric values in the original column (I renamed since my first post last week):

=IF(ISNUMBER([Approved Budget Number]@row), IF(ABS([Approved Budget Number]@row) >= 10 ^ 9, "$" + ROUND(ABS([Approved Budget Number]@row) / 10 ^ 9, 2) + "B", IF(ABS([Approved Budget Number]@row) >= 10 ^ 6, "$" + ROUND(ABS([Approved Budget Number]@row) / 10 ^ 6, 2) + "M", IF(ABS([Approved Budget Number]@row) >= 10 ^ 3, "$" + ROUND(ABS([Approved Budget Number]@row) / 10 ^ 3, 2) + "K", IF(CONTAINS("$", [Approved Budget Number]@row), [Approved Budget Number]@row, "")))), [Approved Budget Number]@row)

This is what it looks like. The green column is the manual entry, gray is the formula.