My take - you need to start small. If you're able to produce a limited quantity and supply it via small independents and build a bit of brand recognition or loyalty, even if it is just locally, then you'll have much more leverage and a track record with the big distributors. It will, firstly, provide evidence that you came up with the idea, and secondly, provide buyers at larger distributors with some confidence that there is a market and you know what you're doing. This might be a way to bootstrap income for development, depending on the product.
The big retailers are the wrong avenue for finding seed capital, I'd say, unless you're prepared to potentially lose control and settle for a whatever they see fit to throw your way. Even if it's a really good concept, actually especially if it is a good concept, you have no bargaining power with the distributors without any of those protections and history shows that they will have no qualms using product ideas, unless it is something that you can actually get a patent or some kind of legal protection for, but then again you need capital for that.