I recently bought two tickets from a seller who claimed he would email me the tickets after payment received. I paid immediately after I won the item but never received the tickets.
I thought I was protected since I paid by paypal. I only found out that was not the case at all after I claimed the seller on paypal and lost the dispute. I called the customer service of paypal and was told that the reason I lost was that the tickets are considered "digital goods". Paypal does not provide buyers any protection for "digital items" since they can't verify whether the buyers receive them or not.
Think twice before you buy tickets on ebay.