Update June 2010. I found this backpack suitable for 2 days trips . It is a bit huge for a one day trekking trip. Where i feel a sub 500 Rs knapsack will do.
The draw back for this backpack is that it does not have an outlet for the hydration pack (good for super long treks.) .For this you can go for the eye back packs from sayonara – bandra
The other options if you do not have any budget restrictions is the wildcraft day packs – their store is at linking road.
More Details Here
Item: Camel Mountain Backpack [Photos]
Dimension: 44cm x 33cm x 19cm
Price: 900 Rupees
Color: Black & Navy Blue
Remarks: Compartment for Your Laptop, Air-Passage Technology to reduce sweat
1 net side compartment
3 external zip compartments
1 internal zip pocket
2nd compartment for laptop usage
Hipbelt for stability
Dual adjust sternum straps
Water Proof Fabric