Even if your RAID a million drives, you're still limited by the network connection to the NAS.
In addition to what MarshallR said there's also 10Gb Ethernet and Fiber Channel options. They're all very expensive setups though. And all (including Infiniband) need networking knowledge.
Also a RAIDR for NAS is rather low storage (specially if you're going Infiniband for it lol). Were you thinking of bundling a few of them together in a Linux box? Cause if that's the case you'd have to use Software RAID anyhow.
So I'll also second that question. What do you need that kind of speed on NAS for? If your tell us more perhaps we can tell you of a decent setup for specific workload.