If someone buys a big EMC system, they aren't just paying for hardware and software. They're paying for EMC to also integrate it into their other systems, set it up, train them to manage it, provide custom coding if their environment requires some unusual change, give early access to fixes for problems they experience, etc. There's a support contract with SLA. There's free overnight shipping of components, and field techs that'll fix the hardware for the customer.
Can someone else do it for cheaper? Maybe. Probably. But to a large degree, it's a "no one ever got fired for buying IBM" situation that you'd be fighting against.
Even if it were possible to do cheaper in budgetary terms, it would be way riskier, and that's a serious factor. I think some technologists tend to overestimate the ability of a (non-technology) enterprise to roll their own (without significant risk and overhead) and underestimate the real costs even just from a budgetary perspective. It's apples to oranges.
Lest this be marketing for price is no object, this doesn't mean anything goes. That's where competition is important. And that includes from open source based solutions and smaller players. The key word is "solution." You can bundle up FreeNAS on your own well rested hardware, customized to the customers requirements and couple it with mucho support, hand holding, and SLAs. Oh, and proving financial endurance of thr organization helps too.Then you might at least be comparing something in the same universe.
Fortune 500 doesn't care about saving 20 dollars only to put the other 80 at risk. And rightfully so.
Can someone else do it for cheaper? Maybe. Probably. But to a large degree, it's a "no one ever got fired for buying IBM" situation that you'd be fighting against.