Kate Holvoet (a librarian at the University of Utah) surveyed 40 International Statistics LibGuides, and came up with the following Top 20 list.
Kate's tips for finding trade data:
1. Between any country & the U.S.: look in U.S. sources first, such as the Statistical Abstract of the United States.
2. Between any 2 international countries: UN Comtrade
3. Between any 2 European countries: EuroStat