AMD F2 series budget gaming build with a A10-5800K. Components below, nothing fancy. In the future (when I upgrade my primary PC GPU) will possibly recycle the Radeon 6850 listed below. I am looking for a PSU recommendation. I typically buy Antec brands from Egghead. Not sure on what size I should be looking for.
AMD A10-5800K Trinity 3.8GHz (4.2GHz Turbo) Socket FM2 100W Quad-Core Desktop APU (CPU + GPU) with DirectX 11 Graphic AMD ...
ASRock FM2A75 Pro4-M FM2 AMD A75 (Hudson D3) SATA 6Gb/s USB 3.0 HDMI Micro ATX AMD Motherboard
G.SKILL Sniper Gaming Series 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 1866 (PC3 14900) Desktop Memory Model F3-1866C10D-16GSR
XFX HD-685X-ZNFC Radeon HD 6850 1GB 256-bit DDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity
Whoa whoa whoa whoa
Are you sure you need 16Gb ram? For gaming, even 8 GB is slightly too much. Decrease the amount of ram to 8 GB though, considering you're building around apu.
As for PSU get a quality one from Antec, Seasonic, XFX, Corsair or PC Power and Cooling, Silverstone. 480 - 550w will be enough.
Why not get a 6670 and crossfire that with that APU. It'll save you some money, enabling you to get faster Ram -- making that APU even faster in games. I'm not too up to date with that, so you might have to do some research, but it might be a good idea.
For your power Supply, anything over 500W, and a brand such as Corsair, Seasonic, XFX, and Rosewill all make great power supplies.