I've seen pairs of just the dual throats, 30172s, sell for $500.

I agree his prices are high, for eBay anyway. He has a lot of Dolby CP200 gear at the moment, the absolute Rolls Royce of cinema sound processors, even by today's standards, yet they are so complex to install and operate they are often junked. The fact that they were 10-20k new in the 80s is irrelevant.