Coming to delhi by train,round trip expense would be around Rs.3000.
Bike rentals are present in karol bagh in delhi, bike charges are mostly Rs.1000/day.
Bike rentals also present in Chandigarh sector 45, u can go with Raghubir bike rentals present there.
At present since manali route will be closed, you need to go through Shimla which is double the distance.
If you have little experience in traveling, I believe 20,000 are enough.