The graphics cards are comparable.
The FX-6100 is a poor gamer, particularly compared to a 3570K.
There is no such thing as a gaming psu, that's hype. I would suspect the quality of either one.
If you can't find out what specific brand/model is being used, I would pass.
To see how much you would save, put together a list of parts along with links.
Then see how much the difference is.
As a rule, you do better building it yourself. And.... the experience is priceless.