How to test a unique idea-Cereal Business

I have an idea for a cereal company that I have been thinking about for some time. I know this business has huge players, and shelf space is extremely difficult to get in grocery stores, and this would be ultra competitive. Is there anyway I could contract a cereal mill or manufacturer to produce a small batch of product I could then test/market to see if the idea would work. I am talking about spending a minimal amount before I take any sort of plunge. I am just in an idea phase, and would like to take some action to see if this idea has any potential. Do cereal companies own their own manufacturing plant/cereal mills? How do the little guys start on a budget? I see some small companies from time to time and startups in small local health food stores, I think this could be a good avenue for my idea, sell to the small local places, give to friends and family and see how the response is. If anyone has any experience or insight I would greatly appreciate it.

By the way my background is in finance/accounting, I have a bunch of ideas I have been accumulating, and I want to start taking some action. Thanks !