Some time back there was a short thread about job scheduling software. I can't remember if it was JobBoss or 4th Shift.
Anyhow there is a white paper out about open source [free] Business Process Management [BPM] and its subdivisions such as Customer Relations Management [CRM], etc. Some of these may only be available in Linux, but that o/s is free also, and you can install on an existing computer with adequate free drive space.
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If you need more drive space, you can generally DIY install a second [or even a 3rd/4th] high capacity drive in an existing computer for c 100$. [Backups/RAID will be critical] for example
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