In terms of buying from dealers - he will recommend you MGA (Maruti Genuine Accessory) Music System from JVC, Pioneer or even Kenwood Option - as they are sold as MGA . Speakers from JBL
However - do note that the Music System you are going to put in (in Single Din or 2 Din) does not come in as Integrated Music System in your price budget. Refer the Attached pic, at the end of reply for comparison of Swift Zxi Music System, which is Integrated and looks awesome on dash and compare with Kenwood Music System, which is Installed as a separate accessory by dealer.
In terms of pricing of Music System for Swift Vxi
> 1 Din System : A Tentative costing is around Rs. 10,000 for Single Din Music System for Swift Vxi, including 4 Speakers
> 2 Din System: Around Rs. 12,500 for JVC & Pioneer. While - from Kenwood - it will cost you around Rs. 14,000 - 15,000. Sony Explod also can be installed in 2
> Integrated Music System : Integrated Music System from Nippon, which is there in Swift Zxi - can also be put in - will cost in approx Rs. 19,500. While from brands like Alpine - it will cost approx Rs. 17,000.
If your budget is less - suggest to choose one 2 Din Music System from Maruti Dealer with 4 Door Speakers. Subwoofer - can be slight expensive to tune of additional cost of Rs. 10,000
Even, if you exceed you budget - the finesse and perfection which is there in factory installed integrated music system is relatively much superior to dealer installed music system.
Note :- If you intend to buy a music system from outside - Benefit is Pricing, you may even get a Kenwood, 2 Din Music System with 4 speakers in range of Rs. 12,000 but do note that after buying a car - dealer can call the warranty void - if installation lead to cutting of wires.
Its recommended - In a smaller budget - will suggest to choose Head-unit in 2 Din Music System with 4 Speakers.