using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var pattern = @"^\$*(?:(?<v>\d{1,3})(?:,(?<v>\d{3}))*|(?<v>\d+))(?<v>\.\d+)?$";
		var tests = new[] {"$100", "$12,203.00", "12JAN2022"};
        foreach (var test in tests) {
        	var result = string.Concat(Regex.Match(test, pattern)?
        	    .Groups["v"].Captures.Cast<Capture>().Select(x => x.Value));
        	Console.WriteLine("{0} -> {1}", test, result.Length > 0 ? result : "No match");
        }
	}
}