I read the posts above and thought I would try to give you a specific blueprint to help:
1) Think about what your app does or what problem it solves
2) Think of 5 questions you would want to ask potential customers to understand what they really want from your app
3) Join twitter and facebook
4) Get a free surveymonkey membership and put your questions in a simple survey _ make sure you ask people if they WANT your app and would be prepared to pay for it
5) Cut and paste the surveymonkey code into twitter and facebook and send messages with relevant words which relate to your target customer
6) Get your results and see what the prospects say and what they want
7) Now sit down and write a word document which outlines what the app does in simple language. Try to keep this first version as clear and simple as possible. You can always make version 2 more complex with more bells and whistles later
8) Go to Scriptlance and find a person to build your beta - you can often do this for under $500.
9) Get your beta out there to trial prospects (see step 5 above)
10) Rinse and repeat from step 4 onwards for version 2 and include existing customers.
....and once you have done this - if you still want investors, take your traction, your beta and your customers which show the potential and sell them on it. And I'd skip the business plan...
Reach out to me if I can help further via www. theFundingGuru dot com
Best of luck and I hope this approach works for you - was getting a little bored of generic funding advice :)
PS - Here's a free report on creating your startup success.