I am thinking to go Nepal end of  september and return in December. Please anybody knowns any travel agency who give better deal. I have heard Turkish Airline offer cheapet ticket to go Nepal is that true? Please advice me, if anybody have a idea. 

You should try land lock travel
It is for people like you they make things very easy for u

About Landlock, you may want to see this discussion.


http://sajha.com/sajha/html/index.cfm?threadid=105027

Turkish air is flying to Nepal (got an email form Zen Travels) and may be cheaper. Suggest to check online by yourself, it will give you a glimpse of you flight and you can choose the timing within 20-40 dollars difference your flight may be more enjoyable.
One of my friend had to stay 8 hours in Dulles Airport ( Washington DC) and 9 hours in NY while returning back.

look online kayak.com best deals
dont go to travel agents .. they are a rip off...

Tips for you after you find ticket say price is 2400 you have to do bargaining and they will reduce the price just like in ratna park or hongkong bazar they say the price of pant is 3000 after long bargaining they will sell at 500 best of luck

When looking for ticket, open up incognito mode in chrome browser and look up at skyscanner.net. The cheapest I found for your criteria was 1330 from turkish, although the trasit time was a bit more. the search as 4th sep -28 dec jfk-ktm rt.
Stay in incognito mode until you complete the purchase because websites like kayak store cookies on your computer to check if previous search occoured. 
Also here is a note from Zen ""In many cases, there is a long layover in Istanbul on the return from Kathmandu.  TK will provide a complimentary hotel if the layover is over 10 hours.  The hotel is outside the airport, so Nepali passport holders will need a Turkish visa to use these complimentary facilities.  For more information on the Turkish visa, please contact the Turkish Embassy website in Washington DC.  American passport holders can get an e-visa quite easily and details are available from https://www.evisa.gov.tr/en/"

Friends, I am planning to travel Nepal at the end of June/ first week July and returning back the end of August from IAD, Washington DC. I am looking for the cheap tickets. Could anyone help me find cheap tickets.