General Knoppix support for those who've read the FAQ at the Wiki
Dell PowerEdge R430 1U Server 2x E5-2690 v3 2.6ghz 24Cores 64gb 4Trays H730 2PSU
$279.99
Dell PowerEdge R730XD 28 Core Server 2X Xeon E5-2680 V4 H730 32GB RAM No HDD
$289.99
Discount Server 24 Bay 4 Node 2U Ea: 2x Xeon 18 Cores 64GB RAM X710-DA4 4x 10GB
$899.00
UNRAID Supermicro 4U 36 Bay Storage Server Xeon 20 Core 3Ghz 256GB X540 10GBaseT
$588.00
Dell PowerEdge R720 Dual Intel Xeon E5-2643 @3.30GHz 128GB RAM No HDD H710P
$124.50
Dell R630 Server 2x E5-2620 V4 2.1GHz =16 Cores 128GB DDR4 1x 960GB 2x 1G 2x 10G
$240.00
HP ProLiant DL360 G9 Server 2x Xeon E5-2690 V3 24 Cores P440ar 128GB DDR4 1x SSD
$279.99
Dell PowerEdge R330 Xeon E3-1220 v5 3.0GHz 32gb H330 2x 3.5" Trays SVR 2012
$189.99
Dell PowerEdge R430 3.5 1U 2x E5-2680 v4 2.4ghz 28-Cores 192gb 4x Trays 2x 550w
$429.99
Dell Poweredge R620 8-Bay 2x E5-2695v2 2.4ghz 24-Cores 512gb H710p 8x Trays
$349.99