I'm not sure what it is that you're looking for, but I just did exactly the google search I suggested above and turned up a thread which reported people's experience buying bikes in Paraguay. I know there are more, because I've seen them, but I'm not willing to search them out for you.
You should also be able to find ample information on buying parts and gear, at least in CdE. Personally, having seen the quality of gear in use in South America, I'd bring my own helmet, pants, jacket, and perhaps boots (depending on what I planned to do). Stuff tends to be either really crappy quality, or really expensive.
All IMHO, of course. Hope that's helpful.