You may find that the easiest part is the actual writing of the plan. The real work comes in the data-gathering, which may take you a hundred hours or more, depending on what you already know or have researched. If your new venture is in an area where you've been working, you may already know about your customers, your suppliers, your marketing plan, your organizational structure, your financial and cash flow needs, equipment, inventory, and so on.
Financial Plan - What is the anticipated income? What are the cash flow projections? What is the anticipated budget over the next 3 years? What is the break even point? When is it anticipated to be met? What funding is needed and where will it come from? What funding is currently available? What collateral is available? What is the net worth of the principals, if applicable? Possible Data Sources: accountant; accounting software; Small Business Administration; Small Business Development Center; SCORE; banks; venture capitalists.
While these are easily available online, some of them are way better than the others. A lot depends on the approach that goes into writing the business plan.
You can find a variety of companies online to help you with your market research. For example: Sundale Research's (sundaleresearch.com) primary goal is to provide new and mature businesses with objective, accurate industry data and market analysis on a wide range of topics. Their market research is intended to save you time and money while keeping up with industry trends.