Purushottam Aggarwal sir is best faculty for ca inter costing. his books covers all the concepts and question from icai study material. teaching technique is also exam oriented and sir provides many short tricks which will help you in exam. Also the best thing i liked about sir is points to remember which helps in revising in exam time.
I am currently studying from CA Purushottam Agarwal pen drive lectures and I feel it’s very good..I have taken the regular one so that I should not miss on any topic..It’s very important to attempt the complete the entire paper to score decent marks..Fastrack batch lectures is also available..you can take your call accordingly..All the best !!!