The ebay auction was a BiN / Make Offer, so placed an offer in for about 60% under the asking price which was accepted.
What i found in the battery compartment was worse than i had expected:
Testing: powered the meter from my bench power supply and made
The photomultiplier tube was an EMI 9902KB and has been disassembled in this video: Teardown: EMI 9902KB Photomultiplier
I may consider sand-blasting the case and having it re-painted.