I ended up going to my LYS the next day (to continue the story as though I haven't let a couple of days go by....), searching for green yarn.
I had decided that since I was ripping out the green anyway, that I'd try to find a closer looking green (so it wouldn't constantly bug me every time I look at it that even though the colors look okay together that they're not right.)
This is what came home with me:
I needed a worsted weight cotton/wool blend but couldn't find any.
Then I saw this yarn at 40% off. Four skeins is enough for a toddler sweater, so that's what I bought.
The saleslady was very nice and didn't question why I was buying a bulky wool when I was making a summer sweater. I felt the need, though, to explain myself so she didn't think I was really going to use them together.
They were the same color, after all.
She didn't think I was a nut, I can now knit another CIC sweater, and I ordered the right yarn when I came home.