Here is a roundup of the costs I had when building this arcade (to the best of my knowledge).  Of course, some of the tools were purchases such as a router and bits and a jigsaw that I plan to use for many more cabs, so not going to include those costs.
$200.00    CABINET (Metal Slug X w/ working 25" monitor)
$39.00      IPAC-2 (Control Panel Keyboard mapper)
$21.00      Arcade Monitor VGA breakout cable/amplifier (converts RBG to VGA and boost power)
$89.00      ArcadeVGA PCIe video card
$120.00    DELL GX260 w/ 1 gig memory and 1 TB HD
$87.00      Marquis and Overlay (gameongrafix.com)
$83.00      Happ trackball (backlit) and mounting Plate
$23.00      Rustoleum 7777 satin black paint and rollers etc.. for cabinet paint
$16.00      40 ft 3/4 inch light blue tmolding (for both CP and Cab)
$17.00      Clear Lexan for protecting CP (better than Plexeglass)
$39.00      2 joysticks and 22 buttons (black and blue)
$35.00      screws, cp hinges, CP  24gauge wire, clips
$13.00      Primer for CP and Cab
$13.00      300 grain and 1200 grain sandpaper
$9.00        1 sheet MDF wood
$7.00       white flourescent light for marquis
$8.00       power supply
$29.00      Logitek 2.1 speakers and sub
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$848.00     TOTAL
The next one I build should be a lot cheaper because I still have alot of the supplies and things, but if you count the tools and bits I had to buy, this MAME cost me around 1050.00 or more.
Gam3rsmurf