I came across an interesting product, NASLite+ from an outfit, Server Elements, that turns pathetic old PCs into servicable NAS (SMB/CIFS, NFS) heads. A 200Mhz Pentium with 64MB of RAM is recommended, and the minimum is a 486, according to Server Elements. It even overcomes BIOS constraints on larger 250GB disks.

NASLite+ is based on Linux with SE’s proprietary additions which explains the lightweight requirements. The price is equally lightweight at $25 for the base version. It is a community workgroup server and doesn’t support disk quotes or much security, but it is fine for storing encrypted backups and the like in a small office.

According to a TechGeeks review

Certainly, this product lacks the sophistication of conventional file
servers and NAS devices. What it lacks in features, it makes up for
in simplicity. Coupled with a client backup software package, NASLite
makes old hardware useful again.

Simple. Cheap. If you are a SOHO/SMB VAR, this could provide you a low entry price for small customers and continuing service revenue. Nothing says [storage] love like turning a worthless old box into a useful tool.