Perhaps you could format your number field with everything but the currency character. Then place a one character calculation field that displays the appropriate currency character.
Sorry, I should have titled this post as "Dynamic Number Formatting", as the problem is not with the actual currency but with the formatting of the price in the number field. The currency is currently stored in a separate field and is not part of the problem.
Let me clarify:
A user enters 5000 as a price (a number field.) For a user in USA, this number field displays as "5,000.00", which is correct, using FMP number formatting (set to 2 decimal places, using "." as the decimal divider and "," as the thousands divider.) For a user in Europe, however, this number still displays as "5,000.00" due to that same number formatting, which overrides the PC regional settings. Basically, I need to display that number field in the right format for users in Europe, which is "5.000,00" (note the difference in the decimal character and the thousands character.)
Any additional ideas? Thanks!