What is the best way to approach people about a potential partnership?
One good step to take is getting a lot of information. Do your research. You should be able to find out the names, addresses and websites of the more important players in your industry, including the manufacturers, distributors, retailers as applicable, and major buyers. That's a web search. Use the same kind of techniques you used to find the Entrepreneur.com website. If you'd like more, there are chapters on researching a market and researching an industry in my free online book Hurdle: the Book on Business Planning. Read them.
Another good step is telephone research. Do the less personal research first, on the web, and then get on the phone. Just guess who to call, but make sure with each person you call who isn't able to answer your questions, you don't get off the phone without asking them who they would recommend you call. Eventually, you'll get answers.