depend how much do you want to spend on meals. There are  plenty of cheap restaurants in Kathmandu and other cities, however beware that it  might make your tummy ache.
When I was there, I did tried this kind of restaurant, but my tummy doesn't like it and I have to eat at the mid to upper restaurants which cost around usd10-20 per meal without drink.

You can eat very well in KTM for $25/day, and can spend a lot more or quite a bit less too, esp. if you like to drink.  Pokhara is similar, but elsewhere it's likely cheaper on average.  If you like dal bhat you can eat super cheap everywhere.

The World Heritage sites all have admission fees for tourists that can add a lot to the daily cost.