You never know what you're gonna get on Ebay. I can't hit your link from the office, but I can tell you OEM engine parts are always a good decision. If you really want to save some cash, I'd highly recommend checking out
Parts Dinosaur. Bruce is a stand-up guy, true to his word, and will make sure you get what you need. (Not that STM, JNZ, or other reputable Mitsubishi vendors would not, but I'm just trying to say saving money doesn't mean a crap shoot, buying from ebay middle men.)
I - and many other gearheads I know - have bought from Parts Dinosaur. I'd highly suggest dropping him a line and getting a quote on a master kit for the 4G63T.