How do I become a supplier for a big retailer such as Wal-Mart, Target, Sears, etc.?
The second way is to go directly to the nearest location of the stores you'd like to sell to and ask to make an appointment to speak with the store manager. Be prepared to answer specific questions about production, manufacturing, quality control, distribution and pricing relating to your product. Be ready to explain the product's relevance and value to the target markets that will be interested in buying the product (toddlers, new moms, tweens, empty-nesters, etc.).
If the conversation goes well, you will be invited to fill out paperwork to submit a request for consideration as a new supplier. Remember that thousands of people are looking to do the same thing you are, so you have to be passionate, prepared and patient to work through whatever system each store has developed.
Best of luck with your endeavor.