M. Honman Called It: Avoid Complexity and High Risk
That was the voice of experience, from one who has also been there.
* High quality and even workstation class PCs are available super cheap coming off lease, typically with a nice Windows 7 Pro license on them. Just look for any Core 2 class processor and 4GB memory. Upgrade as you can.
* Finding someone to troubleshoot their way around a desktop is a lot easier than finding someone inexpensive to troubleshoot elaborate configurations. Virtualization, VDI and Cloudy products rarely mean lower TCO for desktop needs. Adding layers of complexity inherently increases risk of failure in a low-maintenance, lightly-monitored environment.
* Standardize the OS builds and buy a couple of spares to swap out when things go wrong. Your points of failure are distributed, and the swaps buy time to deal with failures.
* Configurations can be adapted to the idiosyncrasies of your requirements. VDI can provide that also, but has a higher cost, maintenance, complexity, etc.
* A high quality NAS, such as a Synology, will provide easy user/security management, lightweight network infrastructure services for a cohesive network and data sharing, and backup options. No server maintenance needed.
Summary: In this kind of environment, failures tend to have a lower impact on the organization. Competent "power users" can keep things running. And issues that would require a tech are still relatively simple, and therefore inexpensive to deal with. In short: Things will generally work, and you'll get to keep your evenings and weekends for yourself.
Good luck.