My process is generally translating in my head whatever I need/want, looking on Mercadolibre, if I can't find it, checking in Google Translate if it might have a different or localized name, and then double checking again.
Once I find something on ML, I then find the vendor's store on Google to see if the price is cheaper buying from them directly since ML doesn't take a cut, and if not, I just buy it from ML.
For anything I can't find, or is too expensive, I just buy via Amazon, ship to Aerobox in Miami, and then pick up at their office here in CABA.
It's a PIA but this is what I've found to be the solution that even Argentine friends and family ask me where to find stuff.