Wordpress query_posts Order By Custom Field
You may try this (hopefully it'll work/found online)
query_posts( "post_type=produkte&".$query_string."&meta_key=Price&orderby=meta_value_num&order=DESC" );
Another answer on SO.
You may try this (hopefully it'll work/found online)
query_posts( "post_type=produkte&".$query_string."&meta_key=Price&orderby=meta_value_num&order=DESC" );
Another answer on SO.