If you are looking to hire a designer then you need to post at http://wordpress.org
Here at wordpress.com no business negotiations can be conducted through use of the forum.
Also note that there are two options on wordpress.com blogs which are hosted by wordpress
(1) use a theme found here -> Presentation -> Themes
(2) purchase a css upgrade and customize a theme yourself
Neither of the options allow for the underlying code to be edited. If you want extensive changes that do require editing of the template then you would be best served to read this as you may be better served by hiring a webhost and having him download a template that can be edited from wordpress.org http://en.forums.wordpress.com/topic.php?id=3700