I've taken GMAT once and from my experience, I'd say one can manage quite comfortably without joining coaching classes. All it requires is diligent effort and about a couple of months of prep. Be choosy about your study materials and that's more than half the job done. As there's no dearth for online resources, one has to be careful in choosing the materials.
Below are the books recommended in most forums.
SC : MGMAT SC and Aristotle SC Grail
CR : Powerscore CR Bible
RC : RC99
Quant : MGMAT Books would do.
Once done with these, go ahead with MGMAT and other online CATs.
This should be more than enough. For more, PM me.
Also, I'd be taking GMAT again this year around Aug. So, count me in for the study group .
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