General Knoppix support for those who've read the FAQ at the Wiki
Dell PowerEdge R730 2x E5-2699V3 2.3Ghz 36 Core 128GB RAM H730 X520-I350 2x750W
$329.99
Dell Poweredge R730xd LFF 14-Bay 2U Server | Choose Your CPU & RAM Config
$509.99
Dell Poweredge R630 Server 2x E5-2620 V4 =16 Cores | S130 | 32GB RAM | 2x trays
$159.99
Dell PowerEdge R730 Server 2x E5-2680 V4 = 28 Cores H730 32GB RAM 8x trays
$356.99
Dell PowerEdge R630 Server 2x E5-2680 V4 = 28 Cores S130 32GB RAM NEW 480GB SSD
$197.99
DELL R630 SERVER 8 x 2.5'' 2X E5-2680V4 32GB RAM IDRAC ENT & NDC 2X 495W PSU
$174.95
Dell PowerEdge R630 Server 2x E5-2640v3 2.60Ghz 16-Core 64GB H330
$182.65
SuperMicro Server 505-2 Intel Atom 2.4GHz 8GB RAM SYS-5018A-FTN4 1U Rackmount
$202.49
DELL PowerEdge R630 8SFF Server 2x E5-2690v4 2.6GHz =28 Cores 256GB H730 4xRJ45
$562.00
1U Supermicro Server 10 Bay 2x Intel Xeon 3.3Ghz 8C 128GB RAM 240GB SSD 2x 10GBE
$259.00