Take your system design and decompose it into unidentifiable parts.
Then, post the parts on elance.com. Use several different names and posting times for your pieces. Ask for bids on how much it would cost to make each part. this will give you an idea about how much it will cost to prototype your invention. Also ask for bids on how much to make 1000 of each part. From that, you'll have an idea about how much your material costs will be. Add them up and see if you can make a business case for your invention at the price of the parts.
If yes, buy them yourself and start selling the product yourself. If you know any venture capitalists, they might become your angel investors after they see a promising product. If it's a good product, people will find you and ask to buy or license the systems for production.