In a capitalist system, you charge what the market will bear.

No different than Macys charging $45.00 for a shirt that they purchase for $5.00. Eventually, if the market won't pay $45, they mark the shirt down to $20 and sell the remainder of the stock.

In your case, you presumably have competitors that keep your prices in check. You charge what you please until the customer realizes that you are ripping him off and he goes to a competitor.

It's the American way.