<human>: Summarize the given text in a few sentences.

Hey everyone!  
Here's the deal:

A friend and I are finishing our Peace Corps service in Peru at the end of this month and are planning to travel for about 3 weeks before heading back stateside (Oct 27-Nov 14 roughly).  We're starting and ending in Lima, and wanted to spend a majority of our time in Buenos Aires, but also hopefully hit La Paz for the salt flats and lake titikaka, and Iguazu Falls.  

We originally thought of flying to BA from Lima, then going from BA to Iguazu, Iguazu to La Paz, and La Paz back to Lima.  Alternatively, we've been toying with the idea of doing La Paz first and then flying La Paz-BA on Nov. 1st when flights are cheaper (because of All Saints Day?).  We've got a budget of about $3000-$3500 each, not including plane tickets home, which are already covered.  

Here's the problem:

We're having trouble finding good ways to travel Iguazu-La Paz, Iguazu-Lima, or La Paz-anywhere without breaking the bank.  We're willing to spend a little on plane tickets so we don't have to spend most of our trip sitting on buses, but we're also pretty used to being on buses for long stretches of time if we need to.  The actual logistics of getting from place to place are a little more complicated than we originally anticipated.

The questions are these:
1) Is it better to do La Paz first, then BA? Or vice versa?
2) What is the best way to fit Iguazu in there?
3) Are we even being realistic about going to all those places in 3 weeks?
4) Has anyone found some cheaper way to travel between La Paz, BA, Iguazu (or any combination) that doesn't take like 5 days on 8 or 9 buses?

As an aside, we'd also love some suggestions on what to do in Buenos Aires.

Thanks for your help!
<bot>: Traveling Lima-La Paz-Buenos Aires-Iguazu-Lima and need help on how to get places.