I also go with Juche, embarked plantless/seedless and refused to trade for agricultural plants/seeds. The whole agriculture in my current fort is based on the glorious cavern plant gathering during the first year of the fort. And since the fort is rich in galena ore, the dwarves learned to appreciate lead furniture. For luxuries I go with sterling silver and billon. But I am less aggressive towards traders, traders are bad, but invasions are worse for fps, clutter etc. so I tend to send them away with gifts. (I will look for an embark or world without elven/human traders in the next fort.)
The whole tangent about war animals is misleading. The best pets are those you trapped and trained yourself (and you can trade away surplus specimen) - my current fort goes with giant cave swallows and the lovely blue centipedes. Buying animals is good for livestock, you don't find in the wild (milk and wool producing animals mainly), hardly for war animals.
I have traded for gypsum plaster, fire clay, rare metals such as tin and iron, exotic fruits for food diversity, leather (when no domestic leather industry), animals (for zoo, sometimes for wool/milk), wood. None of this was really necessary, but I can buy what I need with bone crossbows and voracious cave crawlers.