When I was shopping around for various GMAT Prep courses, I was disappointed at how expensive all of the packages were. But a friend of mine who scored 700 on his GMATs strongly recommended GMATClub along with the GMAT Official Guide, which totaled about 25% of the costs of other leading brands.
I was blown away. On the blog, there are tips and (most importantly for me) different study schedules that you can select. I picked and held to a study schedule, and it prepared me for the exam right on time.
GMATClub Tests are one of the closest simulated mock GMAT Tests available in the market. I have come across some really challenging questions both in Quant and Verbal.
GMATClub is not only for preparation of the exam but for much more. One can keep a track of the schools in which one is applying for.
If you are wondering which GMAT Prep course to get, and you don't need to be one-on-one with an instructor, let me save you some time and money: buy GMATClub subscription along with the official guides.