Took this info off the web:
"In Kathmandu, a hotel bed is not problem unless you are not in times like October-November. A reasonable room with common bathroom with hot shower costs from 200 Rupees/night to 500 Rupees. More luxurious rooms obviously cost more and you can expect to pay up to 1000 Rupees/night for good rooms in some of the well-known hotels in Thamel. Rooms outside Kathmandu are slightly cheaper but around 400 Rupees/night is average price for reasonable rooms with necessary facilities."
So... under 'luxurious rooms' -- 1000 nepalese rupees. That's S$22.
Split it with a travel companion, assuming double sharing.. For about 13 nights.. that's like S$150 for accommodation. Food can be either very cheap, or midrange. Less than S$8 a day should cover it.
Unless you're intending to fly around a bit domestically.. but sometimes the better and faster and cheaper way is to bus it. You said 14 days, so I dont think you really have time to move from one place to another. If you're planning to trek you'll need a lot of time to acclimatize. Annnapurna has one of the highest passes in the world.. if you go up too quickly, and you're not used to Himalayan altitude and weather, you'll get very sick. People die from that. And it's not just the temperature, remember... when I was in the Himalayas the first time, I read "1 degree" and thought, no problem, got there, and then it felt like -20. The altitude and windchill really gets to you. I don't really think you'll have to pay too much to trek either.. I just spoke to a Nepalese guy in my class today regarding the Annapurna trek. Just look around for reputable trekking agencies, no need to sign up with any tours from here.
So if you fly to Nepal for about S$800 something... maybe even max 1K. 2K looks very doable to me!
If you're willing to research.. travel can be very affordable! (And that's why I, a poor student, and do so!)
Good luck.
This looks like a useful website for you.
http://www.gapyear.com/nepal/ideas_of_cost.html