If you don't want to build it yourself, you only have two options:
1. As stated above, go to a local computer store, pick out the parts, and pay them to build it for you.
2. Go to a custom computer website like ibuypower.com or cyberpowerpc.com and order a custom built pc.
Of course, building your own is a much better option.
As far as I'm aware, there's no prebuilt pc that actually have a good graphics card without being stupidly overpriced.