Finasteride is (practically?) OTC. Simply visit a few pharmacies to find one that carries the ultra affordable local brands.
I’ve been using “Finta F.C. tablets” since 2008, without problems. Typically below 150NT per 30pcs if I remember correctly, which lasts around 2 months (~1/3 tablet per day, but I normally just bite one in half)
http://www.nangkuang.com.tw/?route=product/product&product_id=156