I'am sorry to say, but I think You missed the point.
Paypal was never offered any kind of an "insurence" or "refund" about any purchased item, as they were just offered the ability to pay via their company, as Paypal is a money sending company, just like Western Union.
After Paypal was purchased by Ebay, Ebay were created a totally brand new protection system, and it was called "Buyer Paypal protection", but from the very first time it was limited only to the items, which were purchased via Ebay.
In other words, this means, that EBAY is the company WHO takes the responsibility about the goods You purchesed VIA their site, IF YOU USE PAYPAL, and of course Ebay will not take the responsibility in any other cases.
It's just a surplus on Paypal that You can claim about an item, which were not arrived, but as somebody else said: Paypal is just like a bank, they are not a jury, and they hasen't got any resources to investigate a claim about "item not as described".
Anyway I simply can not understand, why You were made this business outside Ebay? If You were agreed in the price, then the regular way is to simply lower the price by the seller, and You can immediately buy it, and pay it via Paypal... I've did it several times, and there was never any problem with it.