No subject in UPSC is low scoring or high scoring.It is the efforts of student which pays. UPSC follow a common platform so that student from any subject course can do well.You can see now how new pattern of UPSC has reduced the weightage of optional and more focussed about students aptitude towards administrative services.So if your good means genuine interest in Commerce and Accountancy and studied it in graduation and take it as a optional paper.Otherwise don't take it.
I am listing some of books
PAPER I
(1) Advanced Accountancy : Sums from B.Com Text Book + Theory � any standard test book.
(2) Cost Accountancy : - S. N. Maheshwari OR C. A. Module
(3) Income Tax : - Vinod Singhania
(4) Financial Management :- Khan & Jain or any other standard text book
(5) Audit : C. A. Modules
(6) A/c CBSE � XI Standard
(7) A/c Standard � Tax manual
(8) IIMS Paper Set Question Bank
(9) Business O & G � Y.K. Bhushan
(10) Audit � CA-Ph-II
(11) OR / OT - L.M. Prasad
(12) Co. Law - M. C. Kutchal + Munish Bhandari (CA)
PAPER II
(1) Organisastion & Management : - L. M. Prasad
(2) Industrial Relations : - Dhanpatrai & Sons publication � Suri
(3) For prelims, refer book hive's � M. N. Arora (Prelims & Mains) + other standard books.
(4) Cost Accountancy � Jawahar lal ,
(5) TataMcGraw-Hill�s
(6) Organisation Behavior � D. P. Robbins
(7) HRM - Ashwathappa
(8) Refer previous year papers of Prelim / Mains