For what it's worth, I bought 2 500GB laptop drives recently (I went with Hitachi Travelstar 5K500.B drives based on various ratings, and avoided 7200rpm for fear of heat/noise/vibrarion issues). Anyway, they were both OEM, in the little silvery plastic envelopes...
The first one I bought from NewEgg and it arrived wrapped in bubble-wrap and stuffed in a box with some styrofoam peanuts. Which the manufacturer's website specifically says would be unacceptable for a warranty return (i.e. send it to us like this and we'll void your warranty). Poking around on NewEgg, I saw a *lot* of reviews (for all different drives) saying, "great drive but newegg's shipping for drives has really gone downhill", or, worse, "drive arrived broken!". *My* drive worked/works just fine (cross fingers), but that was a little worrisome.
The second, identical, drive, I bought from OWC (macsales), and it arrived in the recommended drive packaging, a box with purpose-built plastic spacers with shock-absorbing indentations (Hitachi's site says "sometimes referred to as a GeoSprings Kit"). Anyway, I paid $10 extra to buy the second drive from OWC, and was happier with that experience than I was with NewEgg.
My $0.02.