Proscar is in 5mg strength, while Propecia is in 1mg strength, but the ingredients are the same, both are finasterone. Since the ingredients are the same, why are the prices different? That's because of the patent issues in the production of Propecia, so the price is very expensive, while Proscar is cheap.
The fact is that just cut a piece of Proscar into 5 parts, and the effect is exactly the same as that of Propecia without affecting the effect.