Fellow speaker,
You can promote your product/service by giving away a sample product/service during your talk. When you give away the product/service, make sure to fully describe to the audience what the product/service is, what it is used for, the regular price of purchasing the product/service, and where people can pick up this product/service if they are interested in purchasing it. This will get the interest of the audience in what you have to sell.
Giving,
Tim
