I'm glad to hear that, i'd hate to see the pain of a DIY job when you have stated that funding is not that much of an issue. In fact its probaly a specialist job to even determine the functional specification that you need to meet, so that you can define the tech spec. I'd suggest finding an organisation that can do cradle to grave on this so there is no finger pointing when it goes wrong.
Hopefully someone on here will pipe up and give you are starter for 10.
There's an article on Anantech on building a high capacicty fast server based on ZFS http://www.anandtech.com/show/3963/zfs-building-testing-and-benchmarking
interesting reading and may show you that you need more that this.