Costs are only 10% of the information you need to price your services. The other 90% is the impact, or perceived value, for your customers.

If you only use your costs to come up with a price, you haven't accounted for the impact your services have on your customer. A cost-based pricing strategy will always produce a lower price than a value-based strategy, which means you've left money on the table. Your customer would've happily paid you more than you charged them.

People will make a purchase to avoid pain more often than to gain something.

Think about the last time you bought something. Why did you buy it? Chances are it was to relieve or avoid some kind of pain. Maybe it was gas for your car to avoid the pain of walking for an hour to get work, or maybe it was an email marketing app to relieve the pain of spending hours trying to manually send emails.

When you decide to purchase a specific product or service, you do it because you believe the value (pain relief) you'll receive is more than the money it will cost you.

That's why it's not an accounting question. It's a psychology question. What is the perceived value of the service?