Regex to match only certain characters or strings and only one instance of each?

I feel like I know just enough about Regexes to get stuck. That said, I have an input field which will allow users to enter their currency symbol. I'm only wanting to allow said currency symbol and disallow anything else from being entered into that field. Some countries don't actually have a single symbol, but are just two or three characters, e.g., "Kr" for Krona. So the field has a max length of 3. Given it needs a max length of three to accommodate some currencies, I also don't want to allow three dollar signs to be entered, e.g., "$$$". I would only want to allow one single dollar, pound, euro, etc. sign.

Here's my basic code for allowing only these symbos in the input:

$('#id_currency_symbol').on('input',function (){
    var value = $(this).val().toString();
    newvalue = value.replace(/[^$£€¥₣₩￦￥₽₺₹Rkr]+/g,'');
    $(this).val(newvalue);
});

This works for only allowing these symbols/letters, but like I said above, I don't want to allow users to enter more than a single instance of some symbols, i.e. dollar sign ($). In addition, I want to match exact strings for cases where the "symbol" is actually just two or three characters. In the case of Krona, the "symbol" is Kr. Given the above, users could in theory enter "rK" and it would be perfectly valid according to the regex, but I would ONLY want to allow the exact match of "Kr." Is that possible?

Thanks