Thing with ebay is, sometimes you can find good stuff on there, sometimes things on there are nothing short of junk. These headers in particular seem to be an obscure brand, so they may or may not have the quality of the well known reputable brands. If you are willing to take the risk of buying these and are not too fussy about replacing them if something goes wrong with them, then its up to you if you want to fork out for them. But if you just want to change the headeers once, go for a reputable brand, and pick the style which suits your application better (4-2-1 or 4-1).