Laser cut costs, ventilation & volume control

[Blakey]

The quotes for laser cutting my panels (http://www.arcadecontrols.org/yabbse/index.php?board=1;action=display;threadid=16857) are starting to arrive, I'm looking at around AUD$150 for one to be cut, or ~AUD$80ea for 5. Does this sound fair? I will still have to have the edges routed for t-moulding, been quoted AUD$80 for this.

I'm planning the ventilation now, so far I'm looking at 2 x 120mm 12V fans, possibly run at 7V to reduce noise. Initially I planned to put an intake fan on the bottom, but figured that the motherboard would end up covering it, so I'm looking at placing two on the base of the back panel as shown on the attachment, either both on intake with a passive exhaust out the handles on the top, or one in, one out. Any opinions here? The cab will be running a 1.5-2ghz system and has a 17" monitor. There are no other vents apart from the two handles.

For sound I will be using a Creative 2.1 speaker set, and will replace the satellites with 6" drivers mounted on the front/sides. I want to have a readily accessible volume control, so I figure I can just replace the volume control that came with them with an audio taper pot that has a knob protruding somewhere discreet. Any pitfalls or tips regarding this?

[Blakey]

FWIW, this is the cut layout I've been quoted on:

Thanks for all the advice so far, I'll be putting screw to timber in a week or two, and I can't wait to start construction.

Also, if there's anyone from Brisbane here who'd like a set of panels, let me know.