Atlas of Pilot Charts to download for free
South Atlantic Ocean and North Pacific Ocean are not yet available.
Sailing through the Caribbean, the mantra was "go east". When a new cruiser said, "but xxx is Southeast of here" the reply was, "go east and you might be lucky to make southeast". You might find, as Joshua Slocum did, that it is easier to head to Europe and Africa in order to make it to Argentina.
So my advice to you is to download the pilot charts and study them. Read "Sailing Alone Around the World" by Joshua Slocum.
Cruisers island hop down the Caribbean chain to take advantage of the lee of the islands, sheltered from the strong current and hard winds to make more easting. Look at how Brazil juts out from South America- hard easting.
Reasonably priced charts - well, you can buy photocopies, though they can be difficult to read, at a reasonable price, from Bellingham.
You might also check various marine flea markets for electronic chart chips that would fit your chart plotter.
Charts are expensive, but often you can find used charts offered for sale that are good enough for offshore passages, saving money to buy newer coastal and port charts where the updates might be more important.