Also, wanted to point out that all the people around me who did great on the SAT used only the prep books - none took one of those dedicated classes. Right or wrong, we all thought tutors and tutoring institutes were for struggling students - because none of the top students utilized them. The notion of a great student becoming even better with the help of a tutor was foreign to us. It was only years later did I learn that tutors for top students existed (basically dedicated 1:1 instruction by a "true master").
I got in the elite range simply by buying SAT prep books. I memorized the vocabulary, and the book had enough tricks for me to do well.
Granted, I always excelled in math in school. I, however, did not excel in English (my 10th grade score was a well deserved C). But I still did great on the verbal section, and it was primarily due to reading 1-2 SAT prep books.
If you think you're going to start prepping 1-2 months before the test and do well, it won't work. For both the SAT and the GRE I started about 12 months prior (but very low intensity - a few minutes a day). I did even better in the GRE, scoring well in the top 1% nationally.
If you treat the SAT as a possible golden ticket for your future, you'll take it seriously and start prepping early. If it's merely a "Meh, that thing I need to do to get into a college", no amount of prep will help.