Apples to Apples...
The problem with this is that it compares pricing and not performance and/or management abilities.
If I could buy VSphere at Microsoft's prices, well, yeah, sure, we'd be all over that. However, the premium we pay for VSphere is well worth it in what we save in hardware costs. We've found that we can get nearly 2x as many virtual machines using VSphere as we can with Hyper-V. When you have 3000+ VM's, that adds up in hardware, datacenter, and electricity costs. Also, there is no comparison in administrative tools. If we were forced to use Hyper-V, I don't think we'd be virtualizing - or we'd have to have a MUCH larger staff to administer our cloud.
The other problem is not pricing. The problem is that there are suddenly A LOT more eggs in a basket when you virtualize. So, if you get bitten by some sort of software bug in your hypervisor, you're paying a much higher price than you would otherwise be with a single OS going down. I'm sure that there are a lot of brilliant people at MS, but frankly, we don't trust them for anything this mission critical.