There are many cheap NAS boxes available, but all that I have seen appear as a network drive to Windows. This means they are no use for testing clustering.
One alternative is to download a iSCSI target such as StarWind and install it on Windows. This will give you iSCSI drives you can use on the same or another box to test clustering.
My preferred choice would be to invest in a Technet subscription and install W2008 R2 and build your cluster as virtual servers. Technet will give you access to just about all MS operating systems and server software for non-production use.
Original author: https://github.com/SQL-FineBuild/Common/wiki/ 1-click install and best practice configuration of SQL Server 2019, 2017 2016, 2014, 2012, 2008 R2, 2008 and 2005.
When I give food to the poor they call me a saint. When I ask why they are poor they call me a communist - Archbishop Hélder Câmara