i don't have money for good brands.........
but cheap brands are much cheaper,i mean,can i put a cheap 600-700watt to ensure that it's at least equal to 400watt branded ones?
You can compensate on the power by adding a whole lot more but can you compensate for the ripple, weak rails, PFC and other factors involved in a PSU? Your 550W PSU wont even be able to deliver 20A on its 12V rails. Corsair VX450W delivers a constant power of 33A on its 12V rails plus it can deliver more power than its rated at, i.e. , 450W. I guess you need to do a little bit of reading on what PSU is in modern times. A Corsair CX400W is only 2600 INR and a VX450W is 3600 INR. You can also get Gigabyte Superb 460W at 2200 INR. Which is good.
But anyways, that is upto you.