well a RAID0 of 2 Cruical C300 drives would be about as fast as you'd get without getting just stupid i think. 3 drives wont scale like 2 and you might even be hitting the bandwidth saturation on the bus with 3. I've heard theres a limit of about 667MB/s on a southbridge hdd controller?? http://www.tomshardware.com/charts/ssd-charts-2010/Desktop-Performance-Index-50-Throughput-25-PCMark-25-I-O,2364.html
should show you roughly whats out there and how it performs as you'll see the 256G C300 kicks pretty hard. 2 in RAID0 would see you through for another 5yrs almost.
were you using any third party RAID controllers?