The fastest way to make money on RuneScape would probably actually be Bounty Worlds, even with 0% EP using the 26k method can easily result in getting kills that are worth 60-90k, making it about 35-65k profit per kill (allowing for working with a partner on a 1:1 kill:death ratio). I, and my partner, actually make around 600k/hr each, making this far superior to any other method of gaining money in free to play.