The short answer is that you should really write your own business plan. It sounds like you have already done some market research and understand the size of the market. That's good news! Many companies struggle with that part of the plan.
At this point, the plan should really be your plan, not someone else's plan. Your target market (ie. target customer) will be different than other companies, so a sample business plan won't help you there. Also, your sales forecast and expense forecast will be very different than other companies.
Presumably, because this is a market with lots of competitors, you will need to also have a unique marketing angle. For example, your products might be cheaper or more environmentally friendly than your competitors. Your business plan will need to explain this.
I suggest downloading the free business plan template you can find right here on Bplans.com or using one of your software products. At the end of the day, you will be much better off writing your own plan than reading someone else's plan.