Items in Runescape are varying as time goes by. If you want to earn some money from trading items, you should be aware of runescape market.
Kebabs could be found at Al Kharid from the Karim. Each Kebab just costs 1 gp to buy, but you can sell them for 50gp if you are good salesman.
Another worthy item is lobsters, it is of great use to level high Fishing and earning rs gold so you can buy some from GE and go to Edgeville to sell them for a decent amount of money.
In World 1, you can get some weapons and armors cheap and sell them at higher price if you go to other world.
You can buy flax at the Grand Exchange and then turn it into bowstrings which you can later sell them for profit.
These are some easy way to earn money from trading items. I think as long as you master market analysis, it is as profitable as selling runescape accounts.