To give you a good starting point, I have never done any real woodworking before and I bought the Project Arcade book and joined this forum and everything has turned out great for me and my arcade is almost done. I started this project the first week of September and generally only worked on it during the weekends and I am putting the finishing touches on the project right now. My point is that I have never messed with woodworking very much and I was able to complete this project in a very reasonable time frame, very reasonable cost, and it was a very rewarding experience for me. Cost-Wise, i would estimate that I spent about $1000(all those little trips to the hardware store really add up don't they?) to have my cabinet the way I wanted it. There is a great sense of accomplishment from building it yourself. Not only that, but I know the ins and outs of the cabinet now, so if there is anything that ever needs to be fixed or adjusted, I know exactly how to do it b/c I built it. Doing it yourself also allows you to customize the cab the way YOU want it. I think that wiring the control panel yourself would also be a great experience for you, b/c eventually down the road if you have the cab for a while, I'm sure you'll probably run into a wiring problem and will want to know how to fix it. If you wired it up yourself, you already know what wires you ran where and how. If you ever run into a problem, the guys on this forum are very knowledeable and are always happy to answer a question (as you can probably see already). All in all, I'd say if you have a couple of months worth of weekends to spend and a little bit of patience, I would DEFINITELY build your own cabinet. Good luck.
P.S. Let me know if you need any more specific info on prices and time frames (i.e. an itemized cost chart)