The best buy are shoes,leather goods,coffee, ceramics,sculptures,Indian artifacts,papagaio (parrots)kites,hammocks(a present I always buy when I visit a friend out Brazil,or when a friend come to Brazil),rosewood products and semi precious or precious stones.
The famous ones are Ametist,Opal,Topaz,Citrine,Tourmaline,Emerald,etc..H.Stern jewelry shops is a great example. Brazilian gold is usually 18K. Consider buying Brazilian songs CDs. If you go to Amazonas,the souvenirs are extremely interesting-snakeskins,interesting local grab,”balagandas”(to ward off evil presences) and piranhas(deceased or shellacked).