@deej,
Thanks for the compliment. I built it with AngularJS, which I'm still learning.
Whether or not there are shards shouldn't be a problem; other MMOs like WoW and even Asheron's Call used shards and that wasn't a barrier to community-based data clearinghouses. It just means that each price-point has a larger coordinate tuple: to get (or update) the purchase price of any commodity requires specifying a market name (e.g. "Azeban City") and a server name (timestamps will be managed by the server).
Right now there's no database backend, but I've been working on that. In fact, I've paused development on the app itself because it became immediately apparent that without reasonably timely data, the value of any such app drops dramatically. To that end, I'm building a public REST service for storing and retrieving pricing information. Once the API is complete, anyone who thinks they can build a better trading app can get busy building UI and rely on this service to provide data without restriction. I hope that by building something that's fair and open, I can encourage both the development and player community to focus on maintaining a single data set. I hope to have this wrapped up by the end of next weekend, and then I'll throw it up on Digital Ocean and start handing out API keys to anyone who wants one.