Import/Export Products from one MarketPress store to another

I setup a multi-site network hoping I could sell the same products on each site, just with different branding for our respective resellers. However, I need help copying the products from our Network Admin site to the other sites. We will have hundreds of products listed in our online store in the coming weeks and we need to be able to export the products from the main MarketPress store and import it into each MarketPress store for our reseller sites on the multisite network. What is the best way to go about doing this?