I never buy genuine bags, unless I can get them really cheap, like I did at my local recycling store when they had two packs of genuine HOOVER bags for my Turbopower really cheap.
Otherwise, I log onto eBay, and buy the cheapest (usually Electropart or Qualtex) bags I can, which have never given me any problems nor performed any worse in suction or air filtration opposed to the genuine manufacturers bags.