The Incan Empire wasn't huge on external trade. Prestige goods were often precious metals (which the Empire had in Potosi), sea goods (which it had on the Peruvian coast), and most importantly textiles which it produced itself. As well as this, the Incan Empire's economy was largely inward looking and operated in manors which prioritised existing trade routes. Ayllus (part way between an economic system, a kinship system, and a village) coded their labour obligations in Khipus. Ethnographic literature and some "translations" show us that these obligations largely consisted of supporting groups they already traded with and things like helping Incan "traders" move materials. The movement of materials also can't be clearly seen as trading. Goods were often held in common, either by the ayllu, or in state run store houses. The movement of these goods from location to location was most often the state moving goods from area to area, not the exchange of goods.

Material exchange was primarily based on the idea of reciprocity and obligation. For example someone with food will share it with someone in exchange for labour. The Incan state used this extensively in multiple ways; for example if you sent your daughter to work in the capital making textiles your village would get top tier textiles, or if you agreed to move to the opposite side of the empire and police trouble makers you would get vast tracts of land.

Now this is not to say outside trade didn't occur, when it did it was usually barter economies or labour obligations. But, that it wasn't a significant factor in day to day life. As a concluding thought, one must remember the ethnic tensions that permeated the region and the harsh terrains which would have made long distance trade very hard to undertake.

Main sources:

J.V. Murra, "Cloth and its Functions in the Inca State", American Anthropologist, 64:4, 1962.

S. Hyland, "How Khipus Indicated Labour Contributions in an Andean Village: An Explanation of Seriation, Colour Banding and Ethnocategories", Journal of Material Culture, 21:4, 490-509.

The Huarochiri Manuscript. Edited and Trans. by F. Salomon and G. L. Urioste. (Texas: 1991)

Slightly off topic, but does anyone have a recommendation on books about the Inca that would be non-historian friendly? I love history, but I'm not a historian buff so if anyone has a recommendation of a slightly more pop-history style history of the Inca I'd really appreciate a rec. Thanks.

Follow up:

From what I understand the Inca had a centralized economy with central planning which seems to closely resemble the socialist centrally planned economy of modern and past socialist countries. In fact they seem to follow the ideal communist theory even closer than the recent examples. Is this true?