So I have since had a look at the camera, and run a roll of film through it.
Everything is in excellent condition, the camera even in 'minty' conditon. It was definitely used, but with care.
The light meter works, and seems spot on. The focusing screen is clean, the shutter is sound, and the shutter speeds seem to be on the dot.
I am personally unlikely to use the prism, since one of the things I *like* about TLRs is the layer of abstraction that comes with seeing the subject left-right reversed, but it's in excellent condition. I'm actually more likely to experiment with the Rolleikin, especially seeing as I have a bunch of bulk 35mm film kicking around.
I don't care too much about the boxes either, save that their presence indicates that the camera was stored with care. Everything is squeaky-clean; it's uncanny.
Looking at it, the panorama head is in fact the tripod quick release, which in my opinion is more useful to me than the pano head, seeing as I already have a Manfrotto geared head.
Anyway, while the seller's asking price is a little higher than I had planned, I think I'm going to meet him halfway. Now if only someone had some Bay3 Rolleinars....