You may want to part it out and put it on EBay if you want that price. If a person wants to build a JAMMA cab or a MAME machine and want to go with a prefab cabinet, they aren't going to want to spend an additional 400$ of a new 25" monitor. That's 600$ right there. While the logic you are using is sound (although I think you are being overly optomistic as to what those used parts will bring in an online auction) you aren't taking in to consideration the burdon and costs the buyer has to face.
Look at it this way-- I have a 1972 El Camino in my garage, almost showroom condition. If I were to put it on the open market, I MIGHT be able to get 10,000 for it, maybe more... maybe less. HOWEVER, if I were to completely disassemble the thing and sell it for parts, I could probably get a lot more. You must consider the buyer in this instance as well. When someone is buying a part (say I am selling the front driver quarterpanel) they NEED that part. Original, non-rusted, non-bondoed quarter panels are a rare commodity. I could get a couple hundred dollars for it if I tried hard enough. But if the buyer wants the WHOLE CAR, I won't say, "Well, I could get two hundred for each quarter panel, two thousand for the original bed, two hundred for the transmission..." add all of that up and ask something outrageous for the car. The market just doesn't work that way.
I'm not trying to poop on your parade here, or dissuade anyone from buying your cab. However, this forum is chock full of cabinet bargain hunters so you may want to try selling it to people with a little less arcade cabinet marketplace experience.
APf