Problem on mobile phone resubmitting
no set charge for developing?
As a guide, you can buy SeedCode Complete which handles Contact Management, Project Management, and some other things for about $500.
OTS (off the shelf) prices and custom design prices are two different things entirely. With an OTS solution, the developer hopes to sell to many customers and the development cost can be divided over all the potential customers. Essentially, he can price each copy of the solution more cheaply because expects to sell more than one such copy.
With a custom solution, you deliver one copy and that customer bears the entire development cost. The price you can charge for your services is strictly a matter of negotiation between the two of you. In those cases, you can work out an outline of the scope of the project estimate the number of hours it will take both to analyze the customer's business model and then to design and produce the solution. Decide on how much an hour your time is worth and multiply.
For solutions you offer for sale to the public at large, you have to study the market, price items offered for sale that are similar and set a price you think customers will be willing to spend. The number of established, similar products already offered for sale will be the main factor in what price you can charge and whether or not you have any reasonable chance of selling your solution in this manner.