ICHxR fitted to Intel motherboards are reckoned to cost no more than £5. They are fine for most average PC users for traditional spinning HDD. You are unlikely to saturate the SATA bus with a spinning HDD, because the bus gets to take a break for a few ms while the HDD seeks the next block to be read or written.
SSD drives are a different matter altogether. With access times of around 0.3ms or less, the SATA bus is never allowed to take a break and the bus is soon saturated.
A commercial grade hardware RAID card has many advantages for SSD in RAID.
1, They usually connect directly to the Northbridge via a x4 or x8 PCIe slot, so have massive bandwidth. They also have hardware that does the crunching or they are not dependent on CPU cycles.
2, Most MLC based SSD drives don't have any cache. A commercial grade RAID card does.
Are they worth £200+?
If you can justify it. Yes they are.
Will a £75 do just as well?
Maybe, but most likely, not.
