Would you please tell me what is the MINIMUM amount of power I need to use a PC for gaming with these peripherials safely:

ASRock FM2A85X mobo
AMD A10 5800K APU
2x4 GB ram on 1866 MHz
Sapphire Radeon HD 7850 1 Gb
DVD-writer sata
HDD sata

I've read the Sapphire website and the recommend a 650W PSU to use this video card in a standard PC , though I feel its above the safe amount of power I need here. Can a 450W or 550W handle this setup?

Also I'm looking at Corsair / Seasonic / Antec brands mainly at around 50-90 USD price window.

Thanks for any suggestion.