I'm flying around Oct 15 from Bangkok to Nepal. A friend said the airfare is very expensive: $220 USD one way on Royal Nepal. Is there a cheaper way to get there?

I've heard that the cheapest airfare from Thailand is via Bangladesh Air. You will probably have a stopover in Dhaka, but check them out. Flying to Nepal is expensive - even from India - if you don't buy far in advance, you could end up paying $125 or more from Delhi. In advance, I've seen it for as little as $80 (Sahara Air, Jet Airways or Indian Airlines).
Just a warning about flying to Calcutta (mentioned in the previous entry) - it takes around 10 hours to get from Calcutta to the Nepal border, and another 14-18 hours by bus once you enter Nepal to reach Kathmandu. Unless you have a lot of time on your hands and are in for an adventure, I'd recommend going by air.

I am at the last minute trying to get to Kathmandu in October (2nd week) - spent yesterday with Travel Agent
The "cheap" airfares are not available from Travel Agents overseas at this late date
As a result Dehli to Kathmandu for US$125 would be great but I am quoted US $250
No Thai Air Seats left for Bangkok to Kathmandu and the other options are not available at Travel Agents here
I will be interested as to what you are able to obtain and how much it costs