No body will check how much money you have with you even in the customs. So its a matter of how much money you can exchange in dollars (legally Nepal government will let u exchange what u have to pay to your college for a semester and 1,500 extra from your passport. The rest dollar u will have to buy illegally from Thamel, not a big deal though). But convert the money in travelers check...easy to carry and less risky. dont carry more than few hundred dollars in cash. U can easliy convert the travelers check in bank and the bank wont ask you about where u got the money. So bring whatever u can...just watch the people around at airport, plane and transit.