The cost of a 30-day tourist visa for India is approximately 25$ in consular fees. This fee can be reduced by 15$ during the low season, between April and June. There are different rates for different e-visas: tourism, business, medical.
For those who wish to apply for a visa themselves, please note that any error on the visa application forms or incorrect completion of the form may result in the visa being refused or issued as an invalid visa. The Indian authorities do not reimburse never their consular fees, even in the event of refusal.