You really didn't specify as to what "off the beaten path" means to you, but here are some suggestions. Your budget is also fairly limiting.

For S. America, BA is always a good bet, as is Santiago, but neither are particularly obscure destinations in and of themselves. Also, you might consider Quito and Guayaquil (via Copa or LAN), as they give you access to some great beaches and some gorgeous mountain scenery. They're also dirt cheap and use US currency.

If you can score some cheap tix to Malaysia, I highly recommend Borneo and Sarawak. You might (Probably a bit of a stretch, but I've seen flights for under $1000 on occasion...) be able to wrangle a cheap flight into Kota Kinabalu (BKI)on Korean. Decent hotels there are generally less than $50, and you can stay in a 4 star place for around $100.