using System;

public class Program

{

    public static void Main()

    {

        var original = true;

        decimal prico = 10.000M;

        decimal? price = 0M;

         Console.WriteLine($"{(original ? prico : price ?? 0M):G2}");

 Console.WriteLine(((decimal)(original ? prico : price ?? 0M)).ToString());

 Console.WriteLine(((decimal)(original ? prico : price ?? 0M)).ToString("G2", System.Globalization.CultureInfo.GetCultureInfo("de")));

    }

}