The PSU is the part that is supplying power to your system and is not a part to go on the cheap side with --why risk having it blow up and take the rest of your expensive hardware with it just to save a few $'s ---- In the long run that can cost you alot of $'s to replace an entire system because a cheap PSU with no circuitry to prevent Overvoltage winds up taking down your CPU, Video Card, Memory Modules, and MOBO because you saved a couple $'s !! Stick with a decent PSU from a reputable brand - esp. considering the Power Requirements of a system based on a 5770 GPU is not that excessive so a fairly inexpensive but good quality PSU can be found without spending a lot !
In the countries that are not rich only those who get an i7 930 system buy Corsair, Antec or Seasonic.
If he has the money he can get one of those but otherwise there's lots of good much cheaper brands and it's crazy to get, say a Corsair PSU and a GTS 240 when you can get with the same money a Fortron and a HD 5770.
Fortron, Rasurbo, Sirtec, Gigabyte, Spire, Recom, Silver Power, Cooler Master, Super Flower. etc etc are common in these parts.