How will you provide long term maintenance of their server for a one time payment of 150$?
My current thinking is the margin on the hardware would be intentionally low, essentially the cost of the hardware %+10 for configuring it a bit, installing NixOS, etc.
The business would survive on support and hosted services. Something like $20/month which gets you access to support to answer questions, help configure applications, troubleshoot issues, etc. Possibly rolling upgrades of your installed software on your behalf. Alerts on urgent security vulnerabilities. Could also handle tricky things like custom DNS (email servers, certificates) and off-site backups. I’m not totally sure what all would be included, but the goal is to make money while providing value, not build a garden or rent-seek.