RSorder is the most reliable site to purchase RS Gold (both OSRS and RS3). Based on my experiences (12 years of RMT as the seller and occasionally as a buyer) I have discovered that it is the safest site available. You can trade between other members, which means the prices extremely affordable, and transactions are safer. It's difficult to know which is the source from the metal however If you could locate a legitimate seller of gold, it would be RSorder or a different marketplace site. The majority of stores on the internet can provide something similar.