if you're trying to use Modafinil as a substitute for an amphetamine, you're barking up the wrong bush. Expect the effects to taper off substantially after a few days. Provigil acts on hypocretin/orexin, which isnt well understood, but somehow increases cortical activation... at least in people with a deficiency.
Go to a sleep doc, neuro, or a doc that gives a lot of meds. Chances are they will have a sample of this stuff, especially the sleep doc or a doc that deals with patients who end up in a sleep lab. I think it can be used to treat idiopathic hypersomnolence anyways, so it should be easy to get.