If you are thinking about going to South America on your own, check out South America Explorers first. Membership is not expensive and there are lots of benefits including tour planning and discounts at hotels and restaurants.
Google (or Yahoo!) the Internet for coupons in cities you will be going to. For instance, Google "Chicago coupons" to turn up two-for-one and restaurant and shopping coupons.
Check out eBay for coupons and discounts that others can't use. Type in the destination, such as a city or sightseeing destination (SeaWorld, Disney, etc) and "coupon" and then repeat the search with "gift certificate" instead of "coupon".