Question: (In Nepal)? As a dual Australian-Finnish citizen I read Finns can get a visa on arrival for 15 days. If that's still possible I might just fly to Tehran from Pakistan without any paperwork.
Answer: You can fly to Iran and get a 15-day on arrival visa at the airport. This kind of visa is issued for 98 nationalities excluding USA, England, Canada, Colombia, Pakistan, Afghanistan, Iraq, Jordan, Bangladesh, and Somalia. If your nationality is among the countries authorized to get it, you can collect your visa against offering your passport, a passport-size photo and about $50 to the staff at the airport. There is no need to fill in any form beforehand.
Or fill in the visa form on http://www.uppersia.com/Iran-travel-services/iran-visa.html, it takes about 10 working days to get your reference number and two working days to collect your visa at the embassy by direct referral or one working week by posting the docs to the embassy. You can pay the visa fee in cash in Iran.
Check the cheapest Iran tours at http://www.uppersia.com/Iran-tours