General Knoppix support for those who've read the FAQ at the Wiki
HP ProLiant DL380 Gen9 8SFF Server - E5-2698 v3 - 32Cores - 128GB Ram - 1TB HDD
$299.00
HP ProLiant ML350 Gen 9 Server 64GB RAM 2.4GHz Xeon 12-Core E5-2667 v3
$300.00
DELL PowerEdge R730XD Server 2x E5-2697v3 2.6GHz =28 Cores 256GB H730 4xRJ45
$572.00
Supermicro 2U Server 12 Caddy Bay 3.5 LFF E ATX Storage Chassis SAS2 6GBPS Rail
$199.00
Dell PowerEdge R620 Server 2x E5-2660 v2 2.2GHz 20 Cores 256GB RAM 1x 480GB SSD
$123.19
Lenovo Thinkstation P520 Server XEON W-2135 3.7GHz 64GB 512GB QUADRO P1000
$215.00
Dell PowerEdge R620 Server - 256GB RAM, 2x8cCPU, 120Gb SSD/3x900Gb SAS, Proxmox
$320.00
R630 DELL 8 x 2.5'' POWEREDGE 2X E5-2680V4 32GB RAM IDRAC ENT & NDC 2X 495W PSU
$169.95
DELL PowerEdge R630 8SFF Server 2x E5-2698v3 2.3GHz =32 Cores 256GB H730 4xRJ45
$547.00
DELL R630 Server 2x E5-2698v4 2.2GHz =40 Cores 128GB H730 4x 800GB SSD 4xRJ45
$788.00