Lipstick, PEARLS & cupcakes

When I was living in NYC I was biking through Brooklyn and came across a yard sale. This lady having the yard sale was fabulous and we talked for awhile. She later told she she had been a stylist for years and had collected so much designer stuff and just wanted it all gone. I bought this dress from her. Alexander Mcqueens first collection, off the runway. The detailing inside is obvious it was handsewn and a sample piece. This stylist had no idea Mcqueens death would come only a year later. I want to sell this, I just do no know how much it is worth or where to go. Any suggestions? Comment, message or email briannalmoon@gmail.com.