DataStar accounts have a fixed charge per year plus a prepayment that is offset against usage.
Amounts vary by country.
They show data in varying degrees of detail and many are free. Having used the older TradStat interface, I welcome Dialog's new Web service for trade data. As a single source of trade volumes and prices, Dialog's TradStatWeb is the most comprehensive source of data available, and is now considerably easier to use than the former DOS-based system. The Web interface, with both Guided Search and Expert Search modules, offers many improvements over the previous menu-driven online system. If you have a DataStar password, that's all you need to access TradStatWeb.