• Computer: Casetronic "Travla" C-134 C3 1GHz, 256MB, 40GB
  $500 + $230 for thin DVD/CDRW (thin, I guess, equals expensive)
  You can get a 60GB drive, but the "cost-per-meg" is higher.
  512MB is available, but it was not available when I purchased my PC.
• Keyboard/Mouse: Gyration Wireless Keyboard and Mouse
  $100
• mini-box.com/ituner.com ITPS Power Sequencer and 12V5A Regulator
  $40
• Xenarc 700TSV 7" USB Touch Screen
  $500
• USB "GPS MOUSE" Receiver
  $95
• Sanyo SCP-8100 with USB Data/Charging Cable
  $115
• 2 x 4-Port USB 2.0 Hub
  $45/ea
• Ecovell USB 5V@2A Power
  $17
• Wiring: Custom
  I was very careful to maintain clean reliable fused modular connectors
  Approximately $100

Total: $1,787 (give or take)

This was in mid-2003; you can get most of this stuff cheaper today.
In addition to this cost, my Nissan 350Z came with the $2,000 Navigation option. :(