Smart & simple plan to be more appealing and attractive for buyers of an auction site

Would like to bring BUYERS to an auction Mexican site, our main competitor is [login to view URL], it's a Mexican auction site, like ebay but in Mexico. Our site is under development, however, We're looking for a smart plan to bring buyers; ideas on how this site can be different and more attractive to buyers than our competitor. We're not looking for SEO, Traffic packages, etc. We're looking for a smart plan to bring more buyers and be better for buyer's point of view, buyer's features, for example, one of the features that this site will have, that our competitor doesn't, it's a CHAT between buyers and sellers, where buyers can chat with seller about their listed item. We've a lot of nice features for SELLERS, but we need features and ideas that attract BUYERS and be a benefit for them.