Alternatively Precision Workstations would do.
If that's the route you go, on outlet.dell.com you can filter for just those by choosing Outlet for Work (if you watch the banners at the top you can often squeeze an additional 20%-30% off the already discounted - from the 'build your own' - prices... enough to pay for 3 or 4 year Pro Support Plus coverage, which provides next-day repair service... the 'plus' includes even accidental damage). Be aware though, their Thunderbolt 3 ports might not yet be supported by even C7 unless you're willing to compile new kernels yourself with the proper options enabled (sorry - not sure exactly which options are required). A query about Thunderbolt 3 support in C6 at centos.org/forums/viewtopic.php?f=13&t=57927 asked back in May has yet to attract a response. Sent from my Samsung Galaxy S5