Due to agreements with the patent holder, Cephalon, that were made in 2005-2006 several generics manufacturers are now allowed to sell generic Modafinil. I have found confirmation that the manufacturer Teva has begun selling generic Modafinil, though I haven't seen news about other manufacturers. However, the article also, says that Cephalon is a subsidiary of Teva, so perhaps this won't have an effect? The Modafinil patent is set to expire in April 2015.
The redditor contacted me for advice before officially announcing it and in turn sent me 50 or so Modalert; the packaging was right, and it seemed to work for me. She seems legit... for now.
What probability of the drugs being counterfeit would you be willing to accept? Also, the profit maximizing strategy of the seller might be to initially sell 100% genuine drugs and then slowly lower this percentage.