First question is if these guys are commercial cab builders, how much are they charging you? Wouldn't it be easier to find a good quality ex-Jamma or local cab builder? Outfits like ours surely exist in small pockets on your side of the pond.
Let's just say.... Viva Mexico. I'm Canadian but I've lived down here the last 5 years and when it comes to woodworking - things are *extremely* cheap around here. Monitors, electronics, computers, etc are the same price (or higher) than in the US but for pure carpentry you pay very little.
If I just bought a very high quality normal cabinet new it would cost me 870 pesos. ($63 US) However this would only be big enough for 2 players, and not have all the modifications I want. Because I want... what I want he told me it obviously depends on how much wood is used but the absolute maximum is could cost is 3000 pesos ($219 US - yes, including the CP) It will probably cost a lot less but he didn't want to tell me too low of a price just in case I asked for something ridiculous.
I think it would be fun to completely build it myself but my problem is that I live in an apartment and there simply isn't anywhere to really put the "work in progress" - not to mention the fact that I have absolutely no power tools of any kind whatsoever. I have a hammer and a bunch of screwdrivers..... and that's pretty much it. Heck I need will need to buy a wire stripper to do the wiring on the cabinet!!
I want to make sure I get the design right the first time and if I need any modifications later on well then... maybe I can borrow a drill from somebody.

One of the nice features of the ultimate arcade 2 base design is that when it comes to the control panel... take out 8 screws from under the cp and it's off. (Which by the way is probably the only way I'd get it through the door.) Of course I'm sure most cabinets are like that.