Buying almost all recreationally abused prescriptions on the black market is almost always easier than getting a Doc to get them for you.
I don't know where you live, but in ATL, here is what I've found.
If you REALLY want to get a *legit* script for benzo's, the best doctor to go to is a shrink. 99.9% of the time physicians will start you off on an SSRI or some equally worthless drug for insomnia/anti-anxiety. If you're trying to pass off the need for Diazepam as a muscle relaxer, Methocarb. or Cyclobenzaprine are handed out like candy.
Shrinks seem to be the easiset to get Benzo's from. (For as much as you pay the fuckers they should give you whatever you want!).
In the end, most people resort back to their asshole dealers...or just steal from grandma.