Found a 90mm Congo that has just NOT sold for 100 USD.
From the overall looking it's a single-coated example.
Do a search on Ebay for completed sale, with "Prinz 576" keywords.
Branded Prinz, i.e. USA imported Congo.
Nice Seiko shutter. The seller report the condition as practically new.
I am a large format lens collector, and i own many of the lenses mentioned in this thread. If you want my personal opinion, here it is:
1) I would buy a Congo MC over ANY Angulon.
2) Single-coated vs. single-coated, i'd buy a Congo, IF the Angulon is not a late example.
3) Early non-coated Angulons have a larger coverage, not just because of a different notion of acceptable IQ at the borders, but only due to a design revision in post-war models.
4) For a few different reasons, Angulons made during the fourties/fifties have a much larger amount of duds than later examples. I have a few Angulons with a very late serial, which are impeccable (11 millions or 10 millions serial, i don't remember). I won't go in depth here, but the later the serial, the safer you go.
5) Kodak Ektars HAD a very good QC, compared with lenses of the same vintage (including Zeiss!). You can't reasonably think that the same applies to lenses manufactured from late seventies/early eighties onward! While it's true that some highly regarded lenses were still glued by hand with Canada balsam in the early seventies... it is also true that at the same time a basic aligning tool was becoming available at affordable prices (even for a small company!).
6) For those based in the USA (no expensive shipment, no VAT), one of the Wollensak wides made for Graphic cameras could be worth a try. Quality wise, a 108mm f/12.5 would be preferable, but it's 2 stops slower than the 90mm f/6.3