From India the fares are high, flights are fully booked - usually by Indian tourists - and reservation procedures are chaotic. The only concessional fares are for students. There are flights to Kathmandu from Delhi, Bombay, Calcutta, Patna and Varanasi. The one-hour Delhi to Kathmandu flight on either Indian Airlines or Royal Nepal Airlines costs around US$145.
Kathmandu has some other interesting airline connections; China Southwest Airlines, part of the Civil Aviation Administration of China (CAAC) group, operates a flight from Lhasa to Kathmandu on Tuesdays and Saturdays. This spectacular one-hour flight costs US$190 and is supposed to operate from April to December. You can also fly from Paro in Bhutan on Druk Air, or from Dhaka (Bangladesh).
Lufthansa also operates direct Frankfurt-Kathmandu flights with three flights weekly throughout the year. A return ticket costs around US$825. German bucket shops can produce special deals on these. Pakistan International, Bangladesh Biman and Aeroflot all have a one- airline service from Europe to Kathmandu, though they require a connection in Karachi or Dhaka or Moscow. From Germany, look at charter flights; LTU operates a weekly flight from Germany to Kathmandu during winter.