Dutchdude, don't know if you were looking at the same cab as me, but I just picked up a Captain America cabinet. If the one you were looking as isn't dedicated, and is set up as a Jamma cab (like most of them are), then it can be a really good deal IMO..
The one I got I'll be using the monitor that came with, and only need to put in a trackball and spinner (if I'm felling fancy) and then pick up a J-pac, ArcadeVGA, and Optipac card for the interfacing (or wire it myself.. Not worth it IMO, Ultimarc's cards are a great deal..).
The monitor for Captain America is a 25" low-res monitor (15khz), so it won't work with 720 or Space Ace or other games that require a higher res and sync rate.
Most of the Captain America's are Jamma cabs as well, which is great for Mame conversion!Jamma cabs are soooo easy to hook up to, thanks to the J-pac. And you don't have to butcher the cabinet to get a PC hooked up to a Jamma cab, you can still hook up Jamma game boards to it later if you want, which is super cool.
Side question for the old hats reading this far in - is the ArcadeVGA card REALLY needed if you get the J-Pac? Doesn't the J-Pac already 'thunk' the video signal down to 15khz and boost the signal to ensure good video that can't harm your arcade monitor? What's the benefit of the ArcadeVGA over that? Is it the extra resolutions it supports via it's drivers?
Anyways, it's a really quick and easy conversion from what I'm looking at, and has saved me a LOT of money over building a cabinet from scratch, as well as it looks sooooo much sweeter since all the art and coin doors and such are in, all stuff that just nickel and dime's ya 2 death when building a cab...
If I can figure out a way to get the trackball to not need it's faceplate, I can have it pop up right in the middle of Cappy's shield star, which would look GREAT with the blue illuminated 3" ball..

Go to Mameroom's site for their cab plans, they've got a materials list that breaks down the costs of building a cab in great detail...
IMO building a cab would be optimum, since you'd end up with a cabinet in perfect/new condition (which you'll never find buying a used cab) but the costs in materials and personal time need to be considered seriously... I'm not a carpenter, I'm a gamer, hence my following the dark side - the lazier, quicker, easier, and most importantly - cheaper - route...

Cheers!