What's this machine worth?

I'm thinking of making an offer on this machine. It's at a local machine builder where it is undergoing renovation (among some 30 other machines of different types).

Here's what I know:

3 HP Spindle Motor
VFD
Pneumatic drawbar
NMBT 30
Automatic oiling
Mist coolant
Unknown PC based control w/LCD display (not Mach3)
No conversational or canned cycles, just a plain G-code interpreter
Table is in great condition
Spindle rebuilt with new bearings
New belts on stepper drives
Steppers provide 0.0005 in resolution per step
Machine will be cleaned and surface rust removed
Machine will be detailed and re-painted
Currently wired for three phase power
VFD can do single phase
If I buy it they will rewire for single phase for my garage

Can you help me understand what a fair offer might be for this machine?

I've seen this class of machine online for anywhere from $1,500 (in bad shape) to over $30K (Centroid, etc.). Where would a machine with the above specs and in the stated conditions lie?

Anything specific I should look like?

Yes, they do have the rigid ram version. I simply can't get those machines into my garage. I need to be able to tilt the head, which limits my choices.