How many clients do you run, and what is your monitor setup? (Does the $1k need to include monitors, or do you already have those?)

Regardless, I'd try to wait about a month. Nvidia just announced thier new GPUs, although they haven't really hit the shelves yet. AMD is supposed to announce their new CPUs and GPUs next month. That should mean that next month you'll be able to get a lot more performance for your $ than you do now - even if you stay with the current generations of parts that are out now, those same parts should go on clearance shortly.

Assuming you're talking 5 clients, I'd aim for a 10+ core CPU and a mid-level GPU with lots of RAM.