OK, I'll bite. What is the item and how much does it cost ?
Don't tell me you going to fall for this one...
The "Rare" pattern is known scam method since ages...
Friend of the "buyer" sell the "rare pattern" item in the market which costs cents for much more.
After you buy it, they share the profit from the victim, and they never come back to buy it.
Make sure you read the part "You will get paid once you have the item in your inventory"... That's how they making sure you actually bought that item and spend your money