The list, found by Iraqi News, shows the cost for Christian and Yazidi slaves by age bracket.
A girl aged between one and nine is being sold for £110 whilst a woman between 40 and 50 can be bought for £27.
Thousands of Christians and Yazidi women have been kidnapped by I.S. extremists and it's thought they're being sold off to part fund the group's activities.
The document says: "The market to sell women and spoils of war has been experiencing a significant decrease, which has adversely affected ISIS revenue and financing of the Mujahideen."
It goes on to order the price list be adhered to by everyone or they could face death.
Reports suggest Islamic State holds slave auctions in the Iraqi and Syrian towns of Mosul and Raqqa.
The list could not be independently verified.
