I've found Zepol's trade data to be quite good. I understand Piers also offers a comparable service, although I think they are more focused on bulk imports rather than finished goods, which is probably your interest. They will give you a one week free trial, and their sales follow up is not obnoxious.
I have been using various sources of trade data for years. Currently, I use Global Trade Atlas, which I find very good. It consolidates trade data from more than 60 cuntries, it is user-friendly and the quality of data is as good as provided by the national customs authorities.
I held a presentation on trade data at the SCIP's 2008 European summit. I could share some of my findings with you.
Thanks for the reply. I would be interested in seeing your presentation. One thing in particular that I am trying to understand is company specific imports/exports. For example. how many units of appliances did GE export to Germany... Do any of the sources provide that level of graularity?
As far as I know after many years working with trade data, few national statistics offices offer that kind of detail. Beyond privacy issues there are many others preventing this from happening, like the different Tariff Schedules each country has. They might all be based on the UN Harmonised Tariff Schedule, but up to the six digit, the last four are reserved for individual country adpatations. Then again, even with countries with the same Schedule (customs unions like the EU), any customs official might reclassify any product under a different heading from that under which is was exported.
As if that was not enough to muddle things, differente statistical offices keep different statistics. For instance, some keep track of "wine cases" while many just publish total wine imports by weight. The same can be said for many products that in theory could be counted (like pairs of shoes or refrigerators). Further, in some tiny countries like the Caribbean islands they barely keep records, so they trade statistics are derived from developed-trade partner data (like that in Global Trade Atlas). Other countries do not have the computer power to keep such detailed trade records.
For instance, I once got rough estimates of appliance imports into Venezuela by asking a few importers what the market size was and sort of rounding off their estimates. It came out as "40,000 TV sets, 70,000 kitchen ranges, 150,000 DVD players, .." and so on. Not very accurate but good for complementing the kilogram and Dollar figures supplied by the National Statistics Institute. Just in that format, no brand names, no importer names. Just origin countries and volume (kilo) and value (Dollar data).
As far as I know, Colombia is one of the few countries in Latin America where one could get "complete" information of that sort (importer / exporter name, value, kilogram, and maybe brands), for a fee that is. At the top would be places like Singapore (wtih Electronic Data Exchange before arrival of vessels), some US ports, and probably some European ports like Rotterdam or Hamburg.
My best bet would be to try writing directly to Customs agencies as in theory they collect the Bills of Lading of every shipment, whether paper or electronic, and therefore, they should have that kind of information.