How do I get my invention to market?

I invented a whitewater river product in 2001 and the concept is great. While it is functional, it needs to be professionally engineered so it can be assembled and manufactured efficiently and in bulk. I currently order parts from 5 vendors, and make them in my living room. Without a big bankroll, who do I turn to to get my product designed professionally and ready to manufacture. There is demand for my product as I have sold it to retailers and clients across the country, but my current process is not worth the trouble to keep making them from home. Does anyone know of a reliable source who funds entrepreneurs’ inventions and helps get them to market without the risk of stealing my idea from under me. I know I should patent it and get lawyers, but my funding will not allow it at this time. Any advice?