As far as I know, some people buy the cheaper 5mg pills, meant for prostate hyperplasia (Proscar), and cut it on 1MG dosages to make it last longer.
Here Finasteride is incredibly expensive since only the one manufactured by a major brand is sold (no generics), being 50€ per month. Oddly my Dutasterida from pfizer comes at 33€...
BTW, some people report differences with some finasteride generics, specially with Finnpecia, claiming it changes a lot the texture and look of the hair for the worse.