It sounds like you have a lot of knowlege in this area, and there are lots of pros and cons to be explored. Given the confidential nature of your idea, I would suggest you go to a nearby Small Business Development Center (can find one through www.sba.gov) and talking with a counselor there. They offer professional, confidential business-related counseling and can help you get started with a business plan.

From what I have found a business plan is a great planning tool - not only providing you a place to write down what you are GOING TO DO, but also forces you to look at your opposition (competition, barriers to the marketplace, etc.) and decide how to overcome those issues. Again, an SBDC office counselor can probably offer you some good advice and guide you through this process, as well as offer a business plan template and/or business plan writing(training)classes.

www.score.org is also a great resource for free business counseling from retired business professionals. This might be an option if an SBDC office is not convenient, as you can converse by email with a counselor about the details of your prospective business.

I have used both and been very impressed with the level of information and assistance I have received.

Good Luck!

*GG*