I want to try this medication, as the Dextroamphetamine is not doing the job it used to. Some manufacturers produce medications with sugar pill-like effects while others produce the real thing- any recommendations on Provigil generic manufacturers?

P.S. Provigil Brand $3,026 x 90 day supply / Modafinil Generic $25 x 90 day
Nuvigil Brand $375 x 90 day supply / No generic available, this is a new drug. What is the reason why a newer drug would be cheaper than one that is older and has generics available?