Want to get a pre-made setup, how to judge?

[Hardware]

Hey all! I'm in a conundrum. My handy upgraded-to-death PC has finally met it's demise, due to a very stupid hot-swap error on my part. I've been collecting gift cards for Best Buy from various point-earning programs and I've got about $400 worth. (I can spend more than that, just don't want it to...