Do you want them for use with Airtel? If so, I would advise renting them, because even though you might end up paying more in the long term (i.e. 3 years or more), you will a) Have the peace of mind of having Airtel fix/replace the modem whenever it gets spoiled and b)Have the flexibility to change to another ISP if you want to, and c) If Airtel do get better modems then you can be sure that they would have no hassles upgrading your modem.The rent by the way is Rs. 99 per month.