What's Xen Orchestra? $1800/host/year seems pretty expensive
$1,800 on $130,000,000 a year sounds expensive? Company dinners/outings have almost certainly cost the business more.
The article mentions 4000, so 1800*4000 = 7.2 mil
4000 VMs, not hosts. More likely $3-400k a year before negotiating a volume discount.
VMware enterprise tier is probably 10x more expensive.
Then self-host if the volume you require means you can do it cheaper in-house.