With the removal of RAID functionality Apple Disk Utility in OS X El Capitan, there is no other viable choice: MPG advises anyone using RAID to move to SoftRAID. Fortunately, SoftRAID is far better than Disk Utility ever was.
OWC has SoftRAID Lite for only $34—think of it is a Disk Utility replacement. That said, MPG suggests getting the full version of SoftRAID. Note also that SoftRAID comes with the OWC Thunderbay 4 RAID edition.