Calculating your exam budget is certainly an essential part of your GMAT prep. Are you sure what is actually covered by the test fee? How can unforeseen circumstances affect your GMAT test expenses and what can you do to reduce them? Planning the cost of the actual test taking, without the preparation itself, is certainly step one.
Researching the average GMAT scores submitted in applications for top international business schools can be quite useful in benchmarking and estimating your chances of admission to a particular program. However, they should also be taken with a pinch of salt.
For many people planning to take any of the standardised tests required for admission to postgraduate education programmes, preparation courses are the most obvious choice. For others, not so much. The question is, then, can you prepare effectively for exams as demanding as the GMAT or IELTS without preparation courses?