Nearest Railway station to Nainital is Kadgodham or Haldwani. How are you planning to travel? Flight ? Flights to Delhi being frequent destination might be cheaper. So if travelling from Delhi, you can take train till Haldwani or Nainital. Thereafter hire a vehicle. You can cover places like Nainital & nearby places like Bhimtal, Naukuchiyatal, Pangot, Mukteshwar etc. as per your choice & then proceed to Kasauni. Can include chakori & Munsiyari.