I just got a pair of BIV 1 ribbons from ebay for $380ish and they're a land of contrasts. Pros: fantastic sounding for voice, dead quiet, very sensitive, sound a bit like the voice setting on my voice on the Cloud 44A. Cons: incredibly microphonic, low end rumble like nothing else (picking up a next door fridge), so vulnerable to plosives (pop filter is mandatory), did I mention so plosive-prone that drumming on a guitar could pop it, chrome finish had scratches, the mic body feels/sounds kind of cheap, and there was what looked like plastic stuffed up above the XLR jack when I peaked inside.
Mics are largely how they sound and I really liked the sound, Just in comparison to what I had lying around, I liked the BIV-1 for spoken word as much as a Cloud 44A, SE VR2, EH-R1, Coles 4104, Blue Woodpecker, and Rode NTR. It was leading the pack with the most expensive options. I wish I could redesign the body with a compliant mechanism internal shock mount like the Rode NTR. The body is reminiscent of the straight tube B&O ribbons but not as well fit.
At $230ish/ea. they qualify as great budget ribbon mics. I want more of them, I want to try the BIV 3, but really I want to gut the BIV 1 and design it a new body because the drawbacks in the physical design are very evident.