US singles=Bad quality, 1 little slip of paper, not a very good cover. Singles usually (from the 1999-2001 singles my sister has), usually have ugly covers, and the tracklist is almost always, single+bad remix and/or snippets from the album. Though I guess it's better to just buy US singles like that because the albums are rarely good, so it's better to just buy this single.
^Btw, those singles are all pop ones^
Japanese singles on the other hand, I'll only buy if it's my favorite song ever, with a cool PV or one or more B-sides (Ai Otsuka's Kingyo Hanabi). Sometimes I'll just buy them because of the covers, as well as an awesome tracklist before the album comes out...(Mika Nakashima's LEGEND). You get your money's worth buying Japanese singles.
I only own about 5 singles or so, and the only other ones I plan on buying anytime soon are some Splash Candy singles (*drolls over Chaos of Love Acoustic*), and any new singles Oni or buriguri release anytime in the future.