How do You figure out Monetization?

How did you guys figure out pricing for your users?

About 2 weeks ago we hit a big milestone (number of customers). At first, I was thrilled that we accomplished it. However, I feel like we are not charging enough for what we offer. The product is saving a lot of money for others, but we charge maybe 1/15th of what we save them.

YCombinator or the Zero to One concepts sphere really emphasize charging more, so I guess I'm trying to charge what's fair, but not too much, to seem greedy...

It's a simple online business, that saves money for others.

Advice?

• Specific tools to use to experiment with pricing?
• Any story to learn from the mistakes along the way would be helpful!

thanks in advance!