figure the cost of the materials. Figure how long it took you to make it. Figure how much per hour you are comfortable charging. You may find you have priced yourself out of a job. On the other hand the customers may be happy to get such a wonderful, unique piece of art.
Be sure you let them know, when telling them the price, how much materials cost and how long it took you to make it. Some people think you just whip up something like this in a weekend, they have no clue as to the work and time.