I am pretty sure that ebay is aftermarket, just because you don't consider it so don't mean it ain't so. If the store down the road had it, and this is a store that has a boat load of bikes that they sell for parts, it is considered aftermarket, and a lot of these businesses do the same thing on-line.
"aftermarket" is a term used for manufacturers of products that fit motorcycles, cars, trucks, boats, etc. other than oem products. some joe blow who found a set while cleaning his bench off one afternoon and decided to throw them on ebay is not considered "aftermarket". you've heard of SEMA, right? that is aftermarket. I don't think too many ebay account holders have boothes at a show like that.
the original post re: this was clear- that no one produces these parts (to sell individually), oem or aftermarket. I've got a set on my seat right now. If I sell them, am I considered an aftermarket vendor? no because the parts are oem and I did not produce them either. are parts like these available on ebay at times? absolutely.