Well, the first question again is; what is your budget? That's going to affect everything right off.
Do you have access to wood? Tools? A place to work? A vehicle to move things around?
Wood in NYC:
In Manhattan you've got 2 choices: Prince Lumber (on west 15th,) or Dykes Lumber (on west 44th, I think. A 4'x8' sheet of A/C fir plywood was ~$45 last I was there. No matter the project, you're going to need at least 2 sheets.) In the boroughs and NJ you have assorted Home Depots, Lowes, etc.
Tools: Well, you can get these at any hardware store, even the Home Depots (there's one on 23rd, and one on 57th I believe) in Manhattan have decent selection. Jigsaw, circular saw, router, drill, etc...
A place to work: In Manhattan...?? good effing luck!

I have found one place in Brooklyn, while I haven't been there myself, that looks really interesting:
http://www.makeville.com/ You have to pay to join, and then pay to rent the space (I think you do get some free storage) but it's a fully equipped shop as far I can tell -- no need to buy tools! --- Do you know someone,
anyone, who has a garage you can work in? Otherwise, you're looking at building outside (questionable, especially depending on neighborhood) or building inside an apartment... which is, uh... MESSY. Learned that the hard way.

As far as design goes, I think you might want to shoot for a slimline like Knievel's Woody.
http://forum.arcadecontrols.com/index.php?topic=55789.0 Aside from looking sexy as hell, it's a fairly easy build and it doesn't use a lot of materials.
For controller interfaces and controller parts you've got either Ultimarc.com, GroovyGameGear.com, or Lizardlick.com... all have options that are compatible with consoles.
monitor? (size? 24"? 32"?)
sound?
paint vs. laminate?
artwork? (marquee, sideart?)
t-molding?
plexiglass (what kind?)
etc. etc. etc.
And the guy who's getting the cabinet, what does HE want? Or more importantly, what is he
expecting? And, hoo boy,
WHEN is he expecting it?
Lots of stuff to consider! Welcome to our obsessions.