There are fundamentally two different ways to justify prices:
- Cost Plus Pricing, where you say, "Gosh, it cost us $2 to make this widget, so we are going to sell it for $2.50"
- Value Based Pricing, where you say, "Gosh, this widget saves you $10, so you should be willing to spend up to $9.50 to buy it, because it's still worth it for you."
In practice Value Based Pricing is extraordinarily rare to see in the wild, and you can only pull it off if you are a true monopoly provider. If you are in a market with two vendors and you try to charge for the full value that your product provides, the other vendor can lower their price by one penny and take 100% market share, as long as they are not losing money, so the price rapidly converges on the Cost Plus price.
Thus it's usually safe to assume that your price is going to be based on Cost Plus.
Pricing is a huge and complicated field. Read my blog post Camels and Rubber Duckies for a very superficial primer.