Variegation is certainly rare in catts, and if this plant is otherwise decently healthy / nurturable to a healthy state, it is worth the $90. Personally I could care less, but that's the difference between a collector and people like you and me
For the things that I have a soft spot for, I am generally much more 'flexible' in my critique of overall plant health before purchasing
A similar plant with the same epithet was being sold on ebay 4 years ago (
(check it out) but you can tell from one of the postings on the thread that variegation sometimes seems to spontaneously occur in cattleyas as well. I wonder if this plant is stable in it's mutation.