solution to this question

Best bet here is to shop around. Get personalized quotes from multiple developers, as the price of your app will vary wildly based on what you need it to do. Some may be charging a lot to take advantage of you, but you should be weary of what appear to be great "Deals" as well. Some developers may be just looking for a quick buck by turning over a substandard service. I would recommend trying to find the median/average/typical price from those quotes and go with that one....

Or you can just shake down some of your competitors and figure out how much they paid for their apps, whichever one suits your fancy. Wishing you the best of luck.