What package do IISER graduates get after a BS-MS?

IISERs are not established for just placement purposes rather the motto is to build the scientific aptitude among students so that they earn more from their skills and knowledge. 

The curriculum at IISER has a strong base and you will eventually give up the idea of placements. This is why most students apply for Ph.D. after completing BS-MS from here. Ideally, you cannot compare IIT with IISER in terms of placements as most of the IT companies do not find IISERites to be worthful until they have acquired some skills of their own.

Do not apply here just for the sake of doing engineering as the level of competition is very high at IISER. You will be wasting 5 years if you do not want to pursue higher studies and looking just for placements. 

Even if you look for job opportunities after BS-MS, you can take up jobs as biologists, chemists, mathematicians, physicists with a salary of around INR 50,000 per month.