Took a morning flight from Mumbai to Bagdogra via Kolkata and reached Bagdogra airport by 3pm. Took a share cab to Siliguri bus terminal (300/- outside the airport, prepaid taxi at airport cost 460/- and the counter guy suggested that I take a taxi from outside which is cheaper) where I had booked a room in Hotel Himalayan Regency. I was staying near Tenzing Norgay bus terminal near Siliguri junction as I had to catch a bus to Gangtok the next day (my friend is supposed to join me at Gangtok the next day so had to make a halt at Siliguri). Since there was nothing much to do for the rest of the day, I went to Siliguri junction and the place was almost deserted with a train coming in at an interval of 40-45 min.
We booked our ticket from Guwahati to Newjalpaigudi in kanchanjunga Express for an overnight travel to Siliguri. At Siliguri, bike renting is more competitive than Guwahati but rates are high comparatively. We applied same procedure for stripping down the options, and ended up booking it from darjeeling riders.
NJP Station Parking Lot
Plenty of cars are available at NJP Station/Bagdogra for booking, to drop you at Ravangla. As of April-May 2017, a small car from NJP to Ravangla(Alto/Wagonr) will cost around INR Rs. 3k and a larger one(Travera/Sumo/Innova) will ask you to spend around INR Rs. 4.5k. Calculate accordingly what could be the cost of both options if you have had landed in Bagdogra.