I would build your own, otherwise you'll get lesser capable hardware due to having to pay them to build it. It kinda depends on whether you need everything though. Do you have a copy of Windows you can use, or any peripherals (keyboard, mouse, display)?
If you only need the main tower (Case, MB, CPU, RAM, GPU, PSU, HDD), $1000 would get you a pretty decent setup.
There are some good PC building tutorial videos that also cover OS and driver installs. These things are actually easier than operating and maintaining a PC anymore. Everything is very plug n play now.
Assembly
[video="https://www.youtube.com/watch?v=VIF43-0mDk4"][/video]
OS & Drivers
[video="https://www.youtube.com/watch?v=4zAdwedmj1M"][/video]
If you're OK with plugging a mere 7 parts together that use plugs and sockets that only fit one way, I'll give you a parts suggestion...