Hi there and welcome!
I don't have personal experience with Peru or Ecuador, unfortunately, but from many people I know of who have been to one or both, I would say that would be a good amount of time to see a great deal. Neither of the countries are huge and you could easily start in Quito or Lima and work your way to the other city....
At one point, I was interested in volunteering in S. America and looked into it. I was just searching online to remember the name of the org. I was going to go with, but for the life of me, I can't remember (and there are a lot).
Flights to S. America are usually not cheap; other than the usual search engines like studentuniverse.com, mozilla, priceline, etc. I unfortunately don't have suggestions.
Best of luck!
Flight to Tokyo: 92,000 yen
Metro to Ginza shopping district: 160 yen
Watching middle-aged Japanese woman dance to U2: priceless