Well, there is actual truth in buying tested matched pairs (only from good brands, though, mind you). The cheap brands are most likely a marketing ploy. However, when you get technical, a true matched pair is better than just two spec-matched chips. (Although most people won't be able to tell the difference.)
Also, you'll find that even though the chips state the same specs, the cheaper ones aren't actually the sizes they say. A cheap 128mb stick won't have 128mb worth of actual addressable memory...so yer kinda cheating yourself by going cheap.
