To add a few more thoughts. All BB2's I've seen have the generic WMS glass right above the OLED panel deck. The BB1's are usually theme oriented. For a while there were the BB1.5's, which was basically a BB1 cabinet with a bb2 cpu and an OLED button Deck with dual 19" screens.
If you are handy, you could probably save around 1K buying a BB1 and converting it to a bb2. The hardest part is fitting the 22" monitors into the bb1 cabinet and finding or making up a nice bezel to finish it off. In a nutshell, these are the parts needed:
1. bb2 cpu
2. dual 22" monitors, only the bottom one is touchscreen, the top one is just a monitor.
3. The OLED panel, although this one is not a requirement, but it sure makes your machine look good.
You will need to make the harness to connect the lower monitor and make brakets, bezel, etc in order to fit it into the place where the old 19" monitor was.