It varies. You can always choose to make your trip expensive by staying at fancy
luxury hotels and dining in their restaurants. But then you may as well be in
New York. But if you are looking for a unique Nepali experience, you can do it
for a lot less money.
Traveler's checks is the best and safest option. US dollars are the most widely
accepted form of money, but banks also accept other major international
currencies.
All major banks in Nepal exchange convertible hard currencies into Nepalese
rupees. There is an exchange counter in the Kathmandu airport for you to start
off. The US dollar is the most widely accepted currency. Don't exchange more
money than is necessary for usage in the next couple of days because exchanging
Nepalese rupees back to hard currency is not easy: it can be done only at the
airport before you leave, and only a certain fraction of what you originally
exchanged into Nepalese rupees can be re-converted. Exchanging your US dollar
bills in the black market may fetch a slightly higher rate than what banks would
offer you, but the premium has diminished significantly over the past couple of
years after the Nepalese government liberalized its foreign currency
regulations.
It is important to retain your exchange receipts in order to apply for visa
extension and re-conversion of left-over Nepalese rupees when you leave Nepal.
Many tourist related businesses have started accepting payments in credit cards.
It is, however, a fairly recent phenomenon, and cards other than Visa and
Mastercard may not be accepted in most places. Remember that usage of credit
cards in Nepal can cost you an extra three to five percent in transaction costs.
You can draw funds against your American Express, Mastercard or Visa cards in
Kathmandu. The service premiums for doing this, however, is pretty steep. You
can also have money wired directly to Kathmandu through any major bank within
two to three working days.