My question would be, what is this for? Is this for a learning sandbox so you can get a feel for / practice setting up a fail-over cluster, or is this a QA environment at your workplace, or is this for a production system?

Each of those three will have a different answer, and more questions...

If it's just a learning / practice sandbox, then it depends on the hardware you have available...

It's possible to do this entirely within the hypervisor, if you have access to the right OS. Three VMs, two for SQL, one to function as an iSCSI Target for the shared storage. Or, if you have an external NAS device which supports iSCSI, you could do it with 2 VMs.

If this is for a work environment, now you need to find out what hardware is available, what sort of SLA are you looking at, etc.

Details matter...

The more details you provide, the more someone can help you.