Hey,I have visited the gangtok and North sikkim in April 2018..You can ask any query And for the hotels ,resorts or home stay,download the oyo app.I am using it from last 4 years.You can get hotels at various prices depending on your budget.
And package of 3D/2N will cost you from 2500-3000 depending on your bargaining skills..
Go and ask to to the different travel shops at mall road of gangtok.
Dnt do any prebooking. And have a look on my North Sikkim post on tripoto for some travel tips.