For some strange reason (contrary to other eBay sites, like .co.uk) eBay.com doesn't have the button to select specific country/location. You have to do it manually by going to any listing that also ships to USA, go to the "Shipping & Payments" tab, select USA from the Change country dropdown, put any code (e.g.92104) and press "Get rates". Now you see results like you are from San Diego USA.
Note: Because we have other county's address, eBay will reset this after a while, so we always have to check this and redo it.