Where can I find/buy Peruvian Parsnip (AKA: Batata Baroa or Arracacha) in the US?
Peruvian Parsnips seem to be pretty difficult to find, even online. I found this link that has an "Email me when available" option: https://www.greenharvest.com.au/Plants/SummerLeafyGreens.html#PeruvianParsnip

But the website appears to be in Australia and may not ship to the USA, or perhaps if exorbitant shipping costs. I would recommend to also check local health/specialty food stores, they might be able to special-order it through their supply chain. 

Another option would be to try and find a substitute that would be "close enough". I don't have suggestions as I have never had Peruvian Parsnips. 



Another option: growing them!

I found this link which mentioned growing it.


  Root vegetables are easy to grow for gardeners at any level. In most parts of the country, roots you plan to harvest in the fall and winter need to be in the ground by mid- to late-summer. If you live in a warmer climate, you have additional time. Whether you’re going to squeeze in a few roots this year or are already planning next year’s garden, use these tips for root gardening success. 


Seems like this tuber mostly grows in more tropical climates, so it may be difficult. I also found this other article which has information about growing unusual tubers. 

If you have questions about that, feel welcome to try our Gardening Stack Exchange site!