I’d advise against prep classes for the GMAT. There is really no body of knowledge that they are going to teach you and the tricks really are just a matter of recognizing which method to use (eg, many of the triangle/polygon area problems can be solved by adding a new point to the diagram). The grammar section comes down fundamentally to 20 - 30 rules that you can learn to recognize through practice tests.
If I were you I’d spend my prep dollars on a set of online practice tests. If after doing half a dozen or do, you feel like there is some areas that you aren’t getting, maybe consider a prep course at that point.
If I were you I’d spend my prep dollars on a set of online practice tests. If after doing half a dozen or do, you feel like there is some areas that you aren’t getting, maybe consider a prep course at that point.