Comment by mikewarot

I think that it should be possible to distribute clock lines to at least a 16 channel engine using Tayloe polyphase detectors, which have really good noise characteristics, image rejection, and incredible dynamic range, they also make efficient use of the received signal. One 8 phase clock to feed it all, and coherent downconversion is guaranteed.

Parts cost would be $100 or less via Digikey.