Languages would be xHtml for the structure and Css for styling. For the rest would have to be a language such as Php, ASP, or Ruby on Rails. Would need to use a database such as MySQL of Microsoft SQL Server. Php is the easiest to learn in my opinion and has a lot of ressources on the web as well as most support on hosting services.
as for scripts / open source solutions I dont know of any, but Im sure if you google something such as "open source auction" might find something.