Have you gotten any takers yet?
I can find something reasonable. I work for an IT solutions provider and we also have an active sales account with one of the top 3 vendors.
How new do you want it to be? Does it need to run anything specialized? CAD? Solidworks? 3D?
How many Gb ram? Is storage a priority or do you have a server?
Do you need a monitor as well? What about RAID disks if you don't have a server?
Do you want dual monitor capability? What about supplying monitors?