string input = @"[CODE]{""success"":true,""lowest_price"":""$2.87"",""volume"":""557"",""median_price"":""$2.87""}[/CODE]";
            string pattern1 = @"(?<=\""success\""\:)\w+";

           var result1 = Regex.Match(input, pattern1).Value;

            Console.WriteLine(result1);