Congrats on your idea @Danish, it really sounds promising , considering the huge mobile market india is, even though you are working on it as a single person.
How well do you know your market ?
How many such online mobile stores are you aware of operating on a Pan-India basis ?
How about user behavior ? How many percentage of users buy their mobiles from online stores ? what are the factors apart from deals, ease , online comparison of latest gadgets, reviews (and the metrics around those factors )influencing them to do that
I think you're gonna have a lot of fun making the website , and related functionality for this.
If this is your major pain point, can i suggest contacting the OEM's for these.
All the best, take it slow , take it easy, compete with the best, to become the very best.