I have subscribed GMATCLUB Tests by paying $80 based in feedback of one of my friends. I found Quant test externally helpful for Quant. The beauty of this test is the way in which the explanations are written similar to explanations written by someone attempting quant test and getting Q51. The though process is clearly described in lucid manner. If you wants to score more than Q48 then there is no 2nd thought required. Just brushup your basics from Manhattan or any other book and start attempting 26 quant sectional test. Focus on your weakness based on analytics provided and do some practice questions of weak topic and kill it.
Verbal tests (9 tests) require improvement especially in the area of number of sectional test, quality of GMAT questions like official questions etc. as verbal tests are not close to actual questions in exam.