There are a few cheap self-study books that give you enough vocabulary for the SAT. I don’t think those cram books keep the vocabulary in your head very long, though.
An alternative would be some cheap little books called Spark Notes SAT Novels. They’re not great literature, but they contain the necessary vocabulary for the SAT in natural context, and I believe the words are repeated enough thoughout the story that people remember them. After one or two of those short novels, you should have all your SAT vocabulary. Then you might as well read normal English books, magazines, newspapers and websites.
For business vocabulary, I’d just read the business pages of any good English newspaper. Business Week has a good website, and so does Forbes. There are also some good business articles at startupjournal.com and at collegejournal.com. Both are free services of the Wall Street Journal.