Try this place NorthCoast Custom Arcades
They have a decent number of cabinet designs that ship pre-cut and are easy to assemble like most furniture these days.
Their Upright design seems great for a MAME project, and has a slide out keyboard spot with still having a typical control panel on top.
Yeah, I was checking them out about a year ago and I really do like the look of their upright. My only issue is that when you start throwing in the TV mount, t-molding, coin door, the mount for xarcade controls (if you go that route), and so forth, it gets pretty expensive. Awesome suggestion though and thanks for it too, I almost forgot about them. I'm going to keep looking myself, but if you think of anything else don't be afraid to post. I'm open to pretty much everything. I'm trying to get a hold of an ex-boss that I worked for at a family arcade. Since his business shut down I was hoping to be able to score a machine off of him for cheap (especially MvC2 since that would be perfect), but man, did he ever disappear without a trace.