@fuxx0010, we are still on the hunt for the "perfect" solution. I will note that the Bad Elf Flex now has a base-rover configuration. And, like their GNSS receivers, it is very easy for new users to learn how to configure and use the receivers and radios in base-rover mode, on both iOS and Android. You pay more, but new users need little support to get going. If your users regularly use the same equipment, however, then it may be practical for them to learn how to use a less expensive, but more complicated set up.
Subscription services, like with the Trimble Catalyst or Bad Elf Flex, are a nice option, if your equipment is going to spend a significant amount of the year un-used, or if you generally don't need cm-level accuracy. (And, of course, you are working in area where you can access the subscription.) It often seems to be the case that equipment purchased for individual projects sits on the shelf most of year.
If you are able to share equipment across users and projects, and some work in areas where you need base-rover capabilities, then you are likely going to find it more cost-effective to skip the subscriptions. Instead, get a regular cm-level, base-rover configuration to start with, like Bad Elf Flex Extremes, Reach RS2s, or a more traditional Trimble setup.
Post-processing solutions are great for many use cases as well, but don't work when you need to stake things out.
And, while it is easy to price equipment, it is more challenging to assign a value to users' time or time spent supporting users, particularly as they often come from different budget sources in academia.
I'm also a big fan of obtaining high-resolution imagery, perhaps created by drone mapping relying on access to cm-level accuracy at the start of project, or purchased from a vendor. Folks can then use that imagery in Field Maps on their devices for the remainder of project, and visually locate locate themselves with dm-level accuracy without any need for continued access to a high-accuracy receiver.
Not sure how helpful all those comments are. Those are the kinds of things I think about, but needs can vary so much!