Gaming PC value

Hello there, I'm looking for some pro advice about a computer I saw offered for trade and I wanted some experts ideas on the approximate value of it (So I don't get  ripped) 

It's advertised as a gaming PC and is supposed to be 2 months old. 

Specs.
Windows 7 ultimate 64 bit

CPU:
AMD FX-8320 8 core possessor 


RAM:
8GB dual- channel ddr3 not sure what the brand.


MOTHERBOARD:
Gigabyte 990FXA-UD3 


GRAPHICS:
Sapphire R9 280X 


MONITOR:
ASUS VN247 


STORAGE:
128GB sandisk SSD 
1TB maxtor hdd 


OPTICAL DRIVER:
ASUS DRW 24B1ST C ATA 


CASE:
Fractal design 


Is that enough RAM for a gaming PC? 

Any and all comments and advice are welcome.

This is my first time posting, if this is not the correct forum for this post feel free to move it to the right one. 

Thanks in advance! 

8GB of RAM is good enough.

Overall looks pretty good.  This a quick thing I put together to see how much it'd cost new.

http://pcpartpicker.com/p/qfbhTW

If it's used and in good condition. I'd probably do $750-800 max.