Building a Bluetooth controller, Help and advice needed...

I have seen that while browsing, yet the cost is over $20- for that unit alone. Hoping to find out that there is a low cost, yet completable unit on the market.
I'm not even sure that 2.1 or better is absolutely necessary for compatibly. If it's feasible to use the internals of a Bluetooth dongle then that defiantly seems to be the most cost effective solution. Also there are many types of micro controllers on the market, any suggestions as to whats best for this application. Keep in mind cost effective and that my goal is to have these mass produced.
I'm ultimately looking for a complete breakdown from a engineers standpoint.
There will be a manufacturer engineer involved in the mass production at the very least. I hoping to find some create a understanding of the project for myself.
Hopefully a cost effective prototype can be made that will utilize the same software engineering and hardware compatibly.
I know that my starting point is far fetched but in my heart I believe I have a wonderful Idea for a project that will become professionally built that can and will generate over 100k within a few weeks on Kickstarters generating sales. I am a beginners faze of a mission that I will not give up or turn back on!