PCPartPicker part list / Price breakdown by merchant
This build has a Xeon E3-1231 which is pretty much a rebranded i7 without an integrated graphics card (which is not needed in this build where a discrete graphics card is included). The Quad core with hyperthreading will guarantee crisp performance in graphic design/video rendering and editing. Of course, it has enough power for gaming.
I also included a single stick of 8GB of RAM so you have room for another 8GB of RAM in the future when you can afford it. Of course, if you find that you're not using that much memory when doing your graphic design & video rendering/editing, then you don't have to upgrade it.
The R9 285 has the performance of somewhere between an R9 280 and a 280X. It's a pretty good card that can run ultra settings on most games. If you find that the FPS you get isn't satisfactory, then turning down the filters (anti-aliasing and such) would be helpful. Of course, there will be some games where you will have to turn the settings down to high, but the R9 285 gives you great performance for only $210.
The case is a mITX tower case that has a very unique aesthetic and sleekness. It's a pretty sweet case that doesn't have a bad pricetag.