The seller obviously knows the system and they have cheated you.
As advised, if you open a case with Paypal, you cannot open a case with Ebay afterwards.
Never close a case until you are completely satisfied and have been refunded.
You could always try to sell the item yourself to recoup at least some of your money.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)