Hey Sakshi, If you are starting from Rishikesh and you wnat to complete both spiti and leh, then you would need around 25 k ... well, the exact number of cost can't be presumed ... this will be the minimum you need including food and stay also ... So, from Rishikesh you need to take a bus to Manali first ... and then from manali to kaza ... in kaza you can have 3 days for you to see around ki, kibber, gete, tashigang, chicham and Few more remote villages ... and then two more days if you are interested to check out Parvati valley also ... for that you need to visit mudh Village from kaza ... buses are dre ... If you have an ample of time, then I would suggest you to take a bus to Shimla first from Rishikesh and then go to Chitkul the last village in India and China border and from there to Kaza and come out of spiti valley via ROHTANG pass to marhi ... From marhi you can take a bus to Keylong jispa Sarchu and then to leh ... you do have a direct bus also to leh ... so no need to worry ... Again, no confirmation on money part ... but if you seriously need to cover all lot of spiti valley ... parvati valley... lahaul valley and also leh and surroundings... you would for sure keep 3 weeks with you and your bag packed light ... If you just wanna see and go around kind of ... then you will need 2 weeks ... one in spiti and the other in leh ... also see that almost every place i have mentioned abobe has public transportation ... for your information I have been on a spiti ride last year and here is the link for the sme about the spiti valley :- https://www.tripoto.com/trip/3-guys-2-bullets-1-epic-and-adventurous-bike-ride-of-a-lifetime-to-spiti-valleybestof2018-5c2a6cfc1ed5f Happy and safe Travelling!!!