Prices for hotels and hostels are nearly as cheap as those in smaller cities in India, which are generally the lowest on the planet. It’s worth noting that hotels and guesthouses at the absolute bottom end of the price spectrum will be quite minimalistic, to put it kindly, but paying a bit more gets you something not bad at all. Of course there are now a number of expensive hotel resorts meant for those on much larger budgets, so nearly all price ranges are catered for.
Kathmandu hotels can have big price swings between high season and low season. The busy months generally stretch all the way from April through November, but even then hotels and hostels in the city can be found very cheaply. During the winter months the nights are cool and dry even though the days are still relatively warm, and hotels roll out their bargain rates, sometimes half their high season prices.