I don't believe there are any websites where you can actually buy Celine. You would have to call the retailer and do a charge-send. There's a list of retailers that sell Celine in the "stickies" section up above http://forum.purseblog.com/celine/where-to-buy-celine-664125.html
Actually, after thinking about it - you actually can buy Celine online, but they're not considered "authorized Celine" retailers - websites like BlueFly and Overstock occasionally have Celine bags in stock, but there's no telling what they might have and/or when. There's also hgbagsonline who sometimes has a small selection of Celine and style drops.com is another online site.
"authorized retailers" such as Celine boutiques, Saks, Neiman Marcus, Barneys, Bergdorfs, Nordstroms, Kirna Zebete, etc. dont sell Celne online. These stores will do charge sends tho. You can keep up with what's available and when/where by following the Celine Intel thread above http://forum.purseblog.com/celine/celine-shopping-finds-and-intels-634718.html