using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		    Regex r = new Regex(@"^\$\d+(,\d+)+$");
 
                    string[] partNumbers = { "$567,76", "$567,76,87", "$567,76,87," };
                    foreach (var i in partNumbers)
                    {
                        Console.WriteLine("{0} {1} a valid part number.", i, r.IsMatch(i) ? "is" : "is not");
                    }
	}
}

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