What kind of doradids are you looking for? Some larger LFS order from SA wholesalers and at times they do take requests for fish or collect from a different area to try to find it.
Oxydoras niger are available occasionally, but they get too darned big. I donated mine to the Portland Zoo last Saturday. If you are ever there check him out in the 12,000 gallon Amazon exhibit.
Theres a lot of red tape to get around exporting now from south america. if you can find a imprter already then thats your best bet, ask at lfs for there lists..where are you loacted?