General Knoppix support for those who've read the FAQ at the Wiki
Dell R730 w/ 2x E5-2650v3 10c, 192GB (12x16GB) RAM, H730 Mini, 2x 750W PSU
$499.99
Dell PowerEdge R720 Server - 2x8c CPU,256Gb RAM, 128Gb SSD/3x900Gb SAS, Proxmox
$340.00
$80.00
$599.99
Dell PowerEdge R620 Server 2x E5-2660 v1 2.2GHz 16 Cores 256GB RAM 2x 300GB HDD
$89.99
Dell PowerEdge R730XD 28 Core Server 2X Xeon E5-2680 V4 H730 128GB RAM No HDD
$389.99
SuperMicro Server 505-2 Intel Atom 2.4GHz 8GB RAM SYS-5018A-FTN4 1U Rackmount
$202.49
CTO Dell PowerEdge R630 Server, 2x Xeon E5-2620V4, 64GB- 512GB RAM, 480GB SSDs
$246.67
HP ProLiant DL380 Gen9 8SFF Server - E5-2698 v3 - 32Cores - 128GB Ram - 1TB HDD
$299.00
1U Supermicro Server 10 Bay 2x Intel Xeon 3.3Ghz 8C 128GB RAM 480GB SSD 2x 10GBE
$297.00