Hi, I'm from Viña del Mar - Chile, and I've done some touring across my country. In my last trip (finished a couple of days ago) i cycled the region of "Los Lagos" and passed to Argentina through "Cardenal Samoré" pass. I must say it was a wonderfull trip, lots of amazings landscapes. (Lago Ranco, Rio Bueno, Entre Lagos, Puyehue, Paso Cardenal Samoré, Villa Angostura, Bariloche).
If you want to buy a new bike, Chile is pretty expensive (almost twice the price), so if you have the chance to buy it in USA o Europe dont miss it. If you must buy it here in Chile, there's a street in Santiago called San Diego, it is full with bikes stores.
If you are looking for a good trip in Chile (I know my country) you can look for the "Carretera Austral", its amazin how beautifull it can be.