Unlimited?
This would do well for a start...
System Core
Motherboard Supermicro H8QGi-F
CPU 4 x AMD Opteron (G34) 6386 SE 16-Core 2.8GHz 140W
RAM Kingston 1TB DDR3-1333 REG ECC (32x32GB)
Video Card NVIDIA Geforce GTX 690 4GB
Sound Card Creative Sound Blaster ZxR PCI-E
Controllers SYBA SATA/eSATA II (3.0Gb/s) PCI-Express card
SYBA Firewire 1394a/1394b PCI-Express Card
Silverstone USB 3.0 PCI-Express card
2 x LSI 9271-4i RAID Controller
Networking ASUS USB-BT211 USB 2.0 Mini Bluetooth Dongle
Asus PCE-AC66 Wireless 802.11a/b/g/n/ac PCI-E Adapter
Storage
Hard Drive 4 x Crucial M500 960GB SATA 6Gb/s 2.5inch SSD
4 x Western Digital RE 4TB SATA 6Gb/s
4 x Western Digital RE 4TB SATA 6Gb/s
CD / DVD Asus 24x DVD-RW SATA (Black)
Asus 12x Blu-ray Burner SATA (black)
Removable Drive Atech USB 3.0 Card Reader
Case / Cooling
Case Cooler Master HAF 932 Advanced w/ Extreme Liquid Cooling Package
Power Supply Silverstone ST1500 1500W Power Supply
CPU Cooling 4 x Koolance CPU-380A CPU Water Block
Video Cooling 2 x Koolance Geforce GTX 690 Waterblock
Additional Custom 120mm Windowed Side Panel Fan
Arctic Cooling MX-2 Thermal Compound Upgrade
Additional Chassis Fan
Case Mods AcoustiPack Acoustic Composite Sheet Package
Asus Dual USB and ESATA Bracket
Software
OS Custom Linux-Xen Host
Guests: Archlinux
Debian
Xubuntu
FreeBSD
Peripherals
Monitor 4 x Asus PQ321Q 31.5 Inch 4K UHD Monitor (3840x2160)
Speakers Logitech Z906 5.1 Speaker System
Keyboard Logitech G710+ Mechanical Gaming Keyboard
Mouse Logitech T650 Wireless Rechargeable Touchpad
Ext. Drive 4 x Western Digital USB3 3.0TB External Drive
Notes: Automatic Backup and Restore Set-up
Accessories
Accessories Tripp-Lite OmniVS - 1500VA, 940 Watts
Western Digital My Book Studio Edition II 6TB
SIIG USB 3.0 Dual Head Docking Station
Warranty Warranty: Lifetime Labor and Tech Support, 1 Year Parts
Puget Gear Puget Grey T-Shirt (XX large)
Subtotal: $66,823.49 USD
(Designed via http://www.pugetsystems.com/)
I would also add a dev board from ClearSpeed for their CS301(or whatever they have out that's better) and a full set of CS301(or better) ships...256 of them should do. Last I checked, each chip was somewhere around $1,200 USD. The purpose: the CS301 is a 64-way chip capable of 25 gigaflops(25,000,000,000 floating-point operations per second) on a 200 MHz bus with fairly low power consumption. With the dev board, I could presumably create all kinds of hardware to utilize the chip. Adding it to NICs could allow fast TCP sequence prediction, perhaps SSL decryption on-the-fly, extreme packet generation, etc. Adding it to a video card could..be insane. It would be a password cracker's dream, IMO. Of course, the chip is old so there may be better out by now but rest assured that I would find it.
As a side note, if money were truly unlimited, I would buy multiple systems with similar specs and probably give them out as presents..after I built & populated my lair, of course.
Links & images for mobo & case:
MoBo - http://www.pugetsystems.com/parts/Motherboard/Supermicro-H8QGi-F-6911 (http://www.pugetsystems.com/parts/Motherboard/Supermicro-H8QGi-F-6911)
(http://stolica.ru/pic/s/supermicro.h8qg6f.jpg)
Case - http://www.pugetsystems.com/parts/Case/Cooler-Master-HAF-932-Advanced-w-Extreme-Liquid-Cooling-Package-7972 (http://www.pugetsystems.com/parts/Case/Cooler-Master-HAF-932-Advanced-w-Extreme-Liquid-Cooling-Package-7972)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23049)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23050)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23051)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23052)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23053)
(http://images.pugetsystems.com/images/pic_disp.php?width=1000&height=650&id=23054)
(http://images.pugetsystems.com/images/pic_disp.php?height=650&width=1000&id=18339)
(http://images.pugetsystems.com/images/pic_disp.php?height=650&width=1000&id=23452)