The limitation with a decent RAID array of SSD drives will be your controller and/or your PCI interface. I have servers at work we get ca. 1200MB/sec reads from without any real tuning, while we get ca. 6000MB/sec from a RAM disk (which of course then still costs us the overhead of the filesystem layer). You might be able to beat that with a suitably designed setup, but it's likely to be expensive.
Getting 500-600MB/sec is "cheap". Getting 1200MB/sec gets a bit pricy but isn't hard (the setups we've tested "just" involved us popping 4x OCZ Vertex drives of various models into a server with SATA III, without much regard for anything else).
Getting 500-600MB/sec is "cheap". Getting 1200MB/sec gets a bit pricy but isn't hard (the setups we've tested "just" involved us popping 4x OCZ Vertex drives of various models into a server with SATA III, without much regard for anything else).