Some of the gold can be bought from player who looking to regain some cost of their account.
Trading scam is one of the most popular types of scam, and scammer will open a trade window, then close it blaming lag. Some players will claim that they will quit the Runescape and give away their money. They'll alter the trade, hoping you won't notice that you're not getting what you originally agreed to buy runescape accounts and trade for; they've swapped their side of the trade for a worthless item. They profit by 400,000 and you end up losing money. A lot of players are easy cheated by this kind of scam. Armor that you obtain untrimmed can not be trimmed (Except dragon armor), and you can buy trimmed armor on the Grand Exchange. However, some of the scammers are getting creative, and they will make authentic looking emails to fool the player.
You can find runescape accounts for sale and also get the Runescape gold on the black market at the price of approximately £0.45 per million gold.