There is a mole under neath Falador that is considered a mini-boss that always drops 10K-30K worth of items every kill. The money maker in this method is the Mole is dropping Mole Claws and Mole Skin. The Claws are 9k and the Skin are 10k.

When you go to kill this thing you will need these things...
-Spade
-Light source
-Food/Prayer Potions
-110+ Combat Level to solo
-100 and below I suggest you go with a group

Optional
-Super Sets (Super Strength, Super Attack, Super Defense)

He hits hard so be prepared with high healing food or Prayer Potions while using Protect from Melee.

1.) Start in Camelot bank
2.) Have nothing in your inventory but about 60K
3.) Run south until you find the Fire Making Master
4.) Buy all Tinder Boxes then bank them and repeat the process
5.) Go back to step 1

You buy the Tinder Boxes for 1 Gold. Then sell them at the Grand Exchange for 99 Gold. That is a 98 Gold gain each Tinder Box. Then for every inventory 98x27=2,646. That is a 2,646 profit for each inventory of tinder boxes you buy.

Okay first to find an item in the Grand Exchange. When you find an item click the +5% button two times. So it is 10% above market price, then buy it. Write down what it bought for it is now you maximum sell limit. Then sell it for 10% below market price. Then write down the price it sold for, that is your minimum buy limit.

So lets say I was using Dragon Scimitars I bought it for 98,500 and then sold it for 99,750.

Maximum Sell Limit: 99,750
Minimum Buy Limit: 98,500

That means if I buy it as low as I can, then sell it for the max I can I will make 1,250 profit.

Good items to flip are items that are traded a lot!
If you want to find some items to use, I suggest using the list below.
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From experience I think that Slayer is the most profitable skill. The higher level you get in it the more money you will make.

Good Monsters to kill in Slayer.
Abberant Spectres - Level 60 Slayer - Top Drops: Tortstal Seed, Snap Dragon Seed, High Level Herbs, Clue Scrolls.

Abyssal Demon - 85 Slayer - Top Drops: Abyssal Whip, Clue Scroll.

Dark Beasts - 90 - Slayer Top Drops: Dark Bow, Clue Scroll.

I also made about 7,000,000 gold from 68-71 Slayer. So I strongly advise to people try out Slayer.

Requirements...
Recipe of Disaster Started/Finsished
Shilo Village Complete

Items Suggested...
Ways of getting around
About 50,000 Gold

First go to Lumbridge Castle Basement and right click the Culimancer's Chest and buy all the food you can. Chocolate Bars are mostly the ones you want but the others will help make some pocket change.

Then go to Catherby and talk to the guy at the start of the dock, buy all the Seaweed and Pineapples you can from him.

Then go to Varrock and go to the Staff shop and buy all the Battle Staffs.

Go to Ardougne and go to the General Shop and buy all the boxed Vials and Vials of Water

Go to Shilo Village's General Store and buy all the boxed Vials and Vials of Water.

And you are done. Unpack the Vial boxes and Vial of Water boxes. Then sell everything you bought for a profit.