I'm not aware of any websites that feature clothing worn by stars in movies. However, there is a growing interest in this subject. Often movie stars auction clothes which are associated with films for charity. The clothing has special value to movie buffs because of its association with their favourite films, and can skyrocket in price!
Currently, there is an exhibition at the Victoria and Albert Museum in London of clothing worn by Kylie Minogue in music videos and on tour. The reception that the exhibition has received from the public demonstrates that there are a lot of people who are interested in clothing associated with entertainment.
If there is a particular film you are intereted in, an idea would be to do a search for it on the Internet. Fan sites often cover just about every aspect of films - they may be able to provide information on costumes as well.
Currently, there is an exhibition at the Victoria and Albert Museum in London of clothing worn by Kylie Minogue in music videos and on tour. The reception that the exhibition has received from the public demonstrates that there are a lot of people who are interested in clothing associated with entertainment.
If there is a particular film you are intereted in, an idea would be to do a search for it on the Internet. Fan sites often cover just about every aspect of films - they may be able to provide information on costumes as well.