Hello,
So I can radily find a degassed 15kW lamp for IMAX projectors but that does not help of course.
Reagrding a cheaper source, there is right now a USHIO UWX-15KD for Imax projectors on
ebay for $1400. Still a lots of money but less than the $8000.
It is however rated 15kW only. But i do not think that is too much of a problem. Many Ballast may be dimmed by reducing lamp current. I do not know what your art project needs for a light output, but maybe 15kW is enough.
Most important is that the socket with the cooling connection. If you want, I can take picture os my lamps base, in order to see if it would fit. (I have alredy a 15kW lamp from a imax projector in collection).
Also how publicly present will you art instalation be? If it is public in a big city it may be worth asking Ushio or the superior quartz products inc. to sponsor a lamp...
Regarding your lamps, I would be too very interested in a spare lamp, especially as your lamps seem to bade by the superior quartz products inc. and not by USHIO. I do not have one of these. Shipping would be to Germany or France tho.
best regards,
Alex