HtmlWeb web = new HtmlWeb();
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
HtmlAgilityPack.HtmlDocument doc = web.Load("https://www.ezrsgold.com/buy-runescape-gold");

var buyGoldNodes = doc.DocumentNode.SelectNodes("//buyable-gold");

var buyableJsonList = buyGoldNodes.Select(x => HttpUtility.HtmlDecode(x.Attributes[":buyable"].Value)).ToList();

var buyables = buyableJsons.Select(x => JsonConvert.DeserializeObject(x)).ToList();