I'm looking at setting up a new RAID set now. Firstly, SoftRAID's driver is now included with MacOS, so you should be able to read a set of SoftRAID disks, at least, with no additional software. Also, SoftRAID offer a free version which can read drives and swap disks from your existing sets.
You get 30 days trial of the Pro level product, so that's enough to create your set.