If you've got any designer bags, clothes, or accessories hanging around in your closet and have wanted to sell them but don't know where to start, a new website could have some valuable information for you.Vestiaire Collective, a site that sells designer goods, created a Resale Calculator that estimates the worth of your possessions based on a few key criteria like the brand, material, and color.A cloth black Prada handbag, for example, comes out to $240 on average. A multicolor leather Gucci wallet might be more like $130. Gucci is a particularly good investment right now, according to Who What Wear . The prices of Chanel bags are also on the rise Once you get the estimate, you can post the item on Vestiaire Collective to sell it. The tool could also help you out if you're looking to make a purchase and want to see if you've got a good deal or could sell it for more later.This might finally provide the impetus we need to get rid of those old purses we haven't used since 2010.