What is the minimum amount to buy Ethereum?

Could you please clarify for me the minimum financial commitment required to purchase Ethereum? I'm curious about the entry-level investment for those interested in getting started with this cryptocurrency. Additionally, do exchanges or platforms often have their own minimum purchase limits, and if so, how do these vary? I'm looking to understand the practicalities of buying Ethereum and the potential barriers to entry for smaller investors. Thank you for your assistance in clarifying this matter.