Thanks for asking!
The purpose of the site is to ask and answer questions about the content and the making Movies and TV shows. A question about 'costume' in general would not be off topic if it added to an appreciation of the show - for example understanding that a movie might dress someone in a Saville Row suit to emphasize that they are English and rich perhaps.
However 'trivia' that doesn't really add much to the appreciation of the show - e.g. identifying a suit, is generally considered off topic. This is especially so in the case of purchasing questions - as this information goes out of date as stock changes or retailers come and go. Its not even on topic here to point people to where people can locate and buy movies themselves.
TL;DR : So in short I believe this would not be on-topic here.