So I did some poking around. A lot of the color pics I saw in manga covers varies. Her eyes are often very dark and the only part that has color sometimes is part of the highlight section. But a quicky look I came up with this:
Looking at my covers of Manga vols 6 and 5 in the older larger format release, her eyes are clearly blue. Vol 9, current edition gray. v 32, very dark, v. 11, somewhere between gray and brown. Vol 18, same. vol 4, blue. In the Art of InuYasha, p 2, gray-violet. p. 20, gray. p. 67, blue. pg. 71, gray. pg 76, brown. pg 88, blue.
All the instances where I saw something look brownish, it was in the highlight area, and often was not far away from the color of her sailor fuku collar...reflection or eye color?
Blue/gray seems to dominate. Her eyes are really blue a lot of the time in the manga-based color illustrations that I have available.
Therefore, I will stick with my preference for blue-gray.
Reassured that I am not crazy at what I remembered about her eye color, I will now slink back into lurker mode and go back to being bored....