If you are planning to stay longer you can also apply for Non-Tourist Visa based on "Foreigner of Nepalese origin or such children of a Nepalese father or mother, who have come Nepal to visit their relatives or Father, Mother, Brother or sister of the foreigner married with Nepalese citizen having recommendation letter of relationship from the concern embassy, who have come to Nepal to visit her/him".... Upon arrival get visa for a month and later you can apply for Non-Tourist Visa... I believe it will be cheaper than tourist visa... Check the links below...

Fees chargeable while issuing, or extending the validity of, the non-tourist visa:
1. If the non-tourist visa of 30 days has to be issued at the time of entry, 30 American Dollars or convertible foreign currency equivalent thereto.
2. Nepalese currency equivalent to five (5) American Dollars per month for the foreigner of Nepalese origin and the foreign passport holding child of Nepalese father or mother.
3. In issuing the non-tourist visa to a foreigner who gets married with a Nepalese citizen, Nepalese currency equivalent to ten (10) American Dollars per month.

http://www.nepalimmigration.gov.np/?page_id=88

http://online.nepalimmigration.gov.np/non-tourist-visa-dependent