I emailed Sony asking if i had warranty if i buy a phone from ebay from an international seller and this is the response I got back...
Thank you for contacting Sony Xperia™ Online Support.
We apologize for the delay of our response. In regards to your inquiry, you have a 1 year warranty, however, please keep in mind that any impact or water damage as well as software alteration may void the 1 year repair warranty of your phone, the time frame for the repair is about 14 business days for US and Canadian models and indefinite time for international models, and in case the phone is out of warranty there is a cost.
As part of Sony Mobile's commitment to excellent customer service, we offer a wide variety of mobile products to suit your lifestyle. If you require more information, or have any other questions, please visit [sony website] or call us at 1-866-766-9374.
Sony Xperia US Customer Services