What is the cheapest way to buy ETH?

Could you please elaborate on the most cost-effective method for acquiring ETH? I'm interested in understanding the various options available and how they compare in terms of fees and convenience. Would purchasing through a cryptocurrency exchange be the most economical choice? Or are there alternative methods, such as peer-to-peer transactions or mining, that could potentially offer better value? Additionally, are there any specific exchanges or platforms that you would recommend for making this purchase? I'm looking for a comprehensive yet concise answer that can guide me in making an informed decision.