We have recently updated the app so that Want to Buys are more prominent and useful - users can add a wheel size and bolt pattern they're looking for and they'll receive an e-mail when there is one available.
We have also added functionality for "Feelers" which allow sellers to post up an item that they have to see if there is any interest from buyers. If there is, then they can move to a full listing and add other details like price and pictures.
We've made it so that sellers can list their part locally which buyers within 60 miles can purcahse and there is no charge for local listings.
Try it out:
www.styckyd.com
More on the way.