For GRE examination, every candidate is eligible for taking the GRE - there are no restrictions based on age or qualifications.
The candidate should at least be graduate in any stream.
He should have obtained the minimum pass percentage.
No doubt that a good graduate school will give admission only if the academic record at undergraduate level is good.
Fees for GRE
Test fees for GRE Test may vary according to the country in which you take the test.
In India, this fee is US $190 (approx Rs. 7000), payable at the time of registration. You cannot pay in Indian Rupees. The fees has to be paid through a US Dollar denominated draft, made out in favour of "ETS - GRE" payable in the U.S.
Such a draft is usually available with the Main Branches of most banks (which have a foreign exchange counter) in most of the big cities for a nominal charge (around Rs. 200).
Alternately, the payment can also be made through a credit card which has global acceptance. The credit card need not necessarily be yours - you can get your father to sign for you!