It depends on the price, and the "rights" of ownership to re-sell your work. If I have to pay for development, I would need full ownership to resell the model. OR, You could just design it and sell it yourself. But one person will not fully fund your project without [1]. Knowing the detail of the work you can do, and with the pay only if satisfied of the results. [2]. Having to ability to recoup the cost of the investment by reselling it to multiple X-Plane enthusiasts.