GoAir and IndiGo Airlines fly from Guwahati to Siliguri twice daily. Alternatively, Indian Railways operates a train from Guwahati to Siliguri 5 times a day. Tickets cost $7 - $19 and the journey takes 6 h 5 min.
From Guwahati taxi to Gauhati airport, fly to Bagdogra airport, then taxi to Siliguri. 1 h 41 min $71. From Guwahati (GHY) train to New Jalpaiguri (NJP). 6 h 5 min $16. From Guwahati taxi to Siliguri. 6 h 2 min $118. From Guwahati drive to Siliguri. 6 h 2 min $51.