Not for RAM.
The major manufacturers - Samsung, Hynix, Elpida, Qimonda and Micron are wholesale only. They do not deal with end users and will not answer your emails about warranty. The RAM warranty is through the reseller or through the name-brander of the memory (Kingston, Crucial, etc.) not the manufacturer -- if you even can find out who the manufacturer is. There are hundreds of small assembly houses which solder chipsets onto circuit boards, which are then sold under hundreds of different names (or no name).
You have consumer-direct lifetime coverage from just a few of the major brands like Kingston and Crucial, if the RAM is genuine. But the vast majority of the RAM on eBay is third party generic or bulk RAM and you're going to be out of luck if the seller isn't there.