The patent ended I think now, but smart people were buying cheaper online the whole time. I buy at http://trustworthypills.com and their generic is a good quality at a good price so that's who I personally recommend.
As others have said it really depends on where you buy. Websites are constantly changing and what are good ones before are not today. I buy the generic propecia here without a prescription http://trustedtabsrx.com/ and it's worked just fine.