Kaplan GMAT Advantage - On Site Reviews
Having an instructor is helpful because you can get first hand experience from someone who took the test and did well. They can help you with the strategies they used and teach you in a structured way. Also, for people who learn better in a teacher-pupil environment, this is extremely beneficial. Fortunately, I did not pay the full rate for this course (roughly $1,500) - my employer paid those expenses and I just paid for study materials.