I would suggest a retailer. He is there to do what you want get done - sell it to the end user and provide some after sales service. If you go to a distributor, after sales service could be a problem. But a distributor could give you more discounts because a middle man's (retailer's) margin are not there. Don't expect any after sales service from a distributor.
But I would suggest you go for an assembled PC rather than a branded one. Costs are different and it is easier to have a custom configuration. You can take a search here or participate in some ongoing thread for the right config.
If you are in Mumbai, you can contact me by a PM. I will give you numbers of a few assemblers. Speak to them, take a quote and go with the best of them. Best means not only price wise but also service and realibility wise. I recommend based on my experience, but then you take your final pick.