Hi Abhishek if you are travelling alone , the cheaper option is to get a public transport from Rishikesh to Joshimath. Auli is around 10km from Joshimath. For group travel, hiring a taxi from Rishikesh is better. You can use the same to visit some places enroute to Auli also (maybe get down and click pics).
From Rishikesh you can either take a taxi, generally MUVs like Tata Sumo, Mahindra Max from Rispana Bridge to Joshimath or a bus from ISBT Rishikesh to Joshimath/Auli, the fare is between 500–1000 rs. You have to reach Joshimath from there you can go to Auli by the ropeway (Asia’s highest ropeway, 2015–16 Price Rs 1500/person) or by the roadway. For Skiing, you can contact the GMVN or local guides there. Good Luck.
Hello Abhishek Reaching Auli from Rishikesh is quite easy & you'll have a lot of options.
Choose between taking a Roadways bus or a personal taxi!
My suggestion is to take a bus & contribute in being a responsible traveller :) Cheers✌️