Hey guys. I don't know why I never knew about this, but you can buy tokkul with runes. And if you have karamja gloves, you can buy 1 tokkul with 1 earth, water, fire, etc. rune.
It'd take 260k earth runes to buy 260k tokkul for an uncut onyx. 260k earth runes= ~1.1m. Uncut onyx= ~2.9m.
If you're doing about 4 buy clicks a second (way possible to do more, especially with it in the bottom corner and autoclicker), it takes about an hour and a half.
All you need for this is karamja gloves, which is 40 mining req, and super easy. In order to buy enough runes for 3 hours worth at this rate, you'd need 26 lvl 3 7qp f2p's buying 20k earth runes every 4 hours, so call it 33 for a constant rate. They can also buy other runes for a bit less profit, suddenly making it possible for you to have a bunch of tokkul buyers, raking in dough at 7-10m/hr for an investment cost of your VPS, 33 lvl 3 accounts, and 1-7 karamja glove buyers.
Please, everyone, go crash the in game economy for me if you're a true penny pincher, you can even buy runes at rogue trader for pennies on the dollar.