He's probably doing "dropshipping" with them. Look at their site here:
Drop Ship Dropshipping - buyelectronicstore.com.
So basically he lists the auctions, promotes them, sells them then gets buyelectronicstore.com to send out the goods. Then he gets the commission for the sale. Sorta like a broker - he doesn't have the goods, just the middle man selling on their behalf and getting a cut for the sale.