Yup: Twelve
And I believe it was 3 per domain, plus a bit over overhead.
And yes, I'm sure that they are sitting 90% idle. But I'm not in the position to look at it too close. It was an emergency install, the whole thing done in about 48 hours, from start to finish, and they guarantee our email will never go down due to AD issues ever again.
We will be consolidating domains in about 6 months, at which point most of the hardware will be redeployed.
On hardware pricing side, we got a good deal. Same cost from this all-in-one vendor as our lowest discounted CDW price. These are HPs.