Complete dynamic checkout process in AJAX and PHP

My client is a diamond retailer. The site has been developed on the PHP framework Kohana version 2.3.4. The Website needs a dynamic product selection page. That is, it should change the results returned from a query every time a drop down option is selected, inadvertently changing all other options in the drop down as a given (it needs to work like the eBay selection page: http://www.ebay.co.uk/itm/UNIQ-UK-Womens-Ladies-MAXI-DRESS-Long-Boho-Summer-Evening-Designer-P53-A-/280892739923?pt=UK_Women_s_Dresses&var=&hash=item8710e8e6bc . In that example when color is selected, the sizes not available in that row of the database are grayed out). Here is the link top the page you will be sorting, although at the moment it is not functional: http://www.test.diamgs.com/jewel/jewelInfo/Yasmin#.Ua4lHtIp9kk .The job starts ASAP and has the potential for more work offered based on performance and professionalism. Thanks.