I agree it’s not worth the couple bucks saved. I priced them at a local auto parts $2.89 each. A national chain will not take a chance on cheep imitation... they have too much to lose...I would use caution on buying NGK, and probably other brands, spark plugs on ebay and amazon at bargain prices. Allegedly, there are counterfeit spark plugs being sold as genuine NGK plugs. There are numerous web sites about this issue and ways to spot the counterfeits.
Do an internet search on: counterfeit ngk spark plugs
Also, click on images within that search.
From NGK: http://www.ngk-sparkplugs.jp/english/techinfo/fake/index.html