Finding an import business for sale...

Another question for all you experts out there...

Do you know of any good resources for finding importing businesses to purchase (specifically established importers with large volumes)? I know that there are business broker sites online but I have been unimpressed with many of these sites. Perhaps there are other online resources I can tap? Also, do you think that contacting industry groups would be helpful in discovering buying opportunities? If so, who would you look to contact within those organizations? Any other suggestions?