I've done some work with LCD's before, and I can testify that it isn't easy to get a bare LCD or VFD module from anyone. I ordered some from 2 sources (Varitronix and some other company) and to get the display you want with the correct specs is a chore. These are companies that deal in bulk orders, and ordering one is a pain for them. They are quite expensive at low quantities.

I actually fried a $100 display of mine when I plugged it in wrong by accident. I still have it, I think I know the chip I fried (character generator), but it's SMT and I never got around to finding someone to fix it. These displays are very sensitive.

About the type of display used: Matrix Orbital is the leader in serially controlled displays, but they don't have any graphical VFD's. I've looked for a similar display, and I can't find one (that is serially controlled). There are other 8-bit displays that would work, though, but Noritake has the best variety of VFDs.

The ideal solution for a remote display is to duplicate the current display board somewhat but make it plug into the serial port. You could have a PIC on the display board that would control the VFD via a parallel (8-bit) interface so it would be easier to code for. All the work being done for the display would be done on the board, not in software. The GU128x32-320 looks like a good candidate for this. With a bit of creativity you could duplicate the greyscaling the Empeg team did for the original display.