How much does a ACH transfer cost?

Could you please elaborate on the typical cost associated with an ACH transfer? As a financial consumer, I'm interested in understanding the financial implications of such a transaction. Are there any fixed fees or are the costs variable, dependent on the amount transferred? Are there any hidden charges that I should be aware of? Furthermore, does the cost differ depending on whether it's an inbound or outbound transfer? And how does the ACH transfer cost compare to other payment methods, such as wire transfers or credit card payments? Clarifying these details would greatly assist me in making an informed decision regarding the use of ACH transfers for my financial transactions.