General Knoppix support for those who've read the FAQ at the Wiki
Dell PowerEdge R720 Server - 2x8c CPU,256Gb RAM, 128Gb SSD/3x900Gb SAS, Proxmox
$340.00
Dell PowerEdge R630 8SFF 2.6Ghz 20-Core 128GB Mem 2x10G+2x1G NIC 2x750W PSU
$399.04
Dell PowerEdge R920 24 SFF 4x E7-8891 v2 3.2GHz =40 Cores 1024GB No HDD H730P
$985.00
HP ProLiant DL360 G9 Server 2x E5-2660v3 2.60Ghz 20-Core 96GB P440ar
$304.35
Dell T7810 Workstation 1x E5-2603 v3 8GB RAM Nvidia GPU No HDD OS
$100.00
HP Z440 Workstation 18 Core E5-2699 V3 128GB RAM 512GB SSD 2TB WiFi WIN10 DVD
$216.00
Dell Precision T5820 Barebones Xeon Workstation No CPU/ RAM/ GPU/ HDD DISCOUNTED
$130.00
Intel Xeon Gold 6138 2.0GHz 27.5MB 20-Core 125W LGA3647 SR3B5
$46.00
Dell Precision T5600/t5610 Xeon E5-2670 2.6Ghz 16GB DDR3 RAM NO HDD Nvidia
$90.00
HP Z420 Workstation Xeon E5-2690 v2 3ghz 10-Cores 64gb 240gb SSD 1TB Win10
$134.99