Recently I complete this tour. during new year I was there..
If you going via Delhi, then book a bus through HPTDC (Himachal House ), an overnight journey from Delhi to Manali ( cost will be 1400-1500 per head.) getting off at Bhuntar on the way to manali, then take a local bus to Kasol. You can go for chalal trail, Rasol,Tosh, Pulga.. hotel cost will be 1000-1500 per day approximately.. from there book e cab to Manali will cost you 3000 for a cab..I would like to suggest you to stay at kanhal road side..
over all budget would be 15k approximately per head ( Delhi to Delhi) for 7-8 days..