Getting the customer to buy some additional stuff late in the transaction is called “up selling.” Candy in the checkout line at the grocery store. Extended warranties at the electronics’ store. Rust proofing at the car dealer. These are high margin sales. Some vendors probably make most of their income on the upsell.
So my wife was amused when the term “upsell” appeared in the title bar at eBay’s half.com.
I’m proud to see that she started from somebody’s Amazon wish list and ending up at a much lower cost vendor.