A new gaming PC.
I would basically have to do a complete build from the ground up, as I do not have a previous desktop to pull extra peripherals from.
When you factor in all of the parts needed for the computer itself ($700-$1000 at the least), A good monitor (around $200+), Keyboard, Mouse, Speakers, Headset, A power strip to plug everything into, It comes out to at least $1400.
Oh, and I also need a new desk to put it all on.