Rack mount and priced for SOHO maybe is a combination hard to find. While - in all fairness - every device is rack mountable if you throw 19" shelves into the equation.
If you are into tinkering you may want to check piNAS projects.
What’s the 21st? I have a NAS for storage of all my music (around 5TB) plus automatic backups. Plus when the internet goes out, like it did two days ago when all of Santa Fe New Mexico was out due to some moron in a dump truck… I’m self sufficient.