If you are into summoning, waterfiends could be good to RS gold test. About 80% of the time they'll drop a red charm, and their drops are not that bad either. They are down the whirlpool you obtain access to while performing barbarian training. Be use to utilize crush strikes on them, they're very resistant to any thing else. Bunyips are GREAT here, their special lets you eat raw fish to cure (they drop a lot of them), and if you dont have to cure, you may use the raw fish on it to turn them into water runes (they also drop a great deal of water runes).
Ghostly warriors shed tons of runes, and therefore are fairly good exp, also. All you will need is jenica's ring after completing summer's end, and use the portal near the axe hut. It would be a good idea to bring a fort bracelet on you, in case a rev tries to teleblock you and you can't get into the portal. They respawn extremely fast. If you're in a planet with roughly 1600+ individuals, even just 2 spawns will keep you assaulting none stop. They fall just a couple of runes and gems, so not just the best, but the exp is definitely something to consider.
Guess that about sums it up. Attempt to use super strikes when you're training, you're hit much more often and gain considerably more exp\hour. Another fantastic \cheap method is to utilize a dbaxe special, then drink a restore potion, then top it off with an assault potion. Cheaper than using the superb strengths, however, it will about like a project. Probably a few great things I didn't understand about\forgot to mention. The methods I have come up with are Buy 1000 Nature Runes (-219k). Mine 1000 Iron ore and 2000 Coal and Supeheat (+635k). Profit of 416,000 a 1k steel bars Or Purchase 1000 Nature Runes (-219k). Mine 600 Mithril ore, 400 Iron Ore, 3200 Coal (+960,800). The first method is quicker to OSRS buy gold mine, but I'd need to do it more often. Second method will get me close to 69 smithing though. In case you've got a better method please let me know.