Yah, the yellow brick road should be red and yellow, not purple and yellowish-green.
I'm not enough of a guru to tell at a glance whether that's only a matter of tweaking, or a symptom of more serious problems. In general, any CT-100 with a live CRT is worth more than one with a dud, of course.
Before plunking down that amount of $$, I'd want to get more details from the seller (who did the restoration and when, what did they do, etc.). But I assume any serious bidders already know that.
Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html