It seems there is success with the Sillicon Image 3132 controller, and it's variants - cheap companies. I think you can get one for like 25$... Search this forum to find the thread with more information. Like you said there is also the RocketRaid option.. After that, from what I know you have to buy an expensive real hardware RAID like ARECA or 3WARE.
From a technical standpoint, I spent some time looking at how we could port existing Linux/Fbsd drivers for fakeRaid like our JMicron/ICHx etc... It would be very interesting to see what subclass these drivers implements. I know the SI3132 is using IOSCSIParallelInterfaceController, but what about the RocketRaid one? I searched the whole forum to find an ioreg of someone having these controllers without any luck... If anyone with either a Highpoint or SilliconImage card comes by this thread and see this, could you help this cause, by doing a quick "ioreg -l".