How to(and should you) purchase a 3G data card/dongle in India

Having shopped for prepaid dongles in Mumbai and Bangalore, besides having spoken to dealers, distributors and company executives(not just Airtel), I think this post can give some insight and save people money while purchasing data cards.

1. As telecom operators do not have a pan India 3G license, they resorted to reciprocal roaming arrangements where the big3(Airtel, Idea, Vodafone) offer free roaming in data to their subscribers across India. So an operator offering 'free pan India roaming' may not be an USP. But benefit from this if the tariffs in your home state is different from that in the destination state. The arbitrage opportunity could exist nevertheless
2. Negotiate the maximum free usage(and its validity) from your operator. For example, if MTS offers 10GB free for 1mth with data card costing just Rs 999, then others may be prevailed to do so. How it works is that the distributor gets a good commission, and may spend some of that giving you that extra top-up, which may not cost him that much. 
3. Be aware of the lapsation norms of the prepaid data card. You may need to recharge it within a defined period. Longer it is, the better for you in terms of flexibility.
4. Though not strictly legal/ethical, some stores charge Rs 100-200 to 'unlock' the dongle' to use SIMs of other operators, thus allowing subscribers to go with the cheapest plan across operators while still using the same dongle. That increases the churn quotient of the subscriber
5. Remember that promised speeds are indicative and depend hugely on your location. So speeds upto 7.2Mbps may amount to just 2-3Mbps if you are lucky.  So do not spend too much on an operator's plan/prepaid data card before testing the speed in your location. Remember, quality of service/speed are not grounds for a refund under TRAI regulations. 
6. For usage>6GB/9GB,a wifi hub may be cheaper, or even a broadband connection. Explore those options if you are a heavy user. 

Hope this was useful!