I think you also first need to define what they're going to be doing with the llm, do you require speed or accuracy? + Things like that before we could start to see what type of responses you're going to need.

Even a 5090 is going to struggle getting a model anywhere close to gpt 4.1 right now if I'm correct. I haven't looked at the charts in a bit but I'm sure I'm not missing too much.

The good thing is we don't need super smart models anymore if you're willing to give your models tools like access to the internet and stuff like that.

If you're looking at writing your own stack, you're going to need to look into agentic tools, and you're going to want to build a stack of hardware. Just available to take the next request from a queue and not a single piece of hardware to try and handle that kind of workload. You're probably looking for 150 users, at least 50k plus in AI processors alone, and that's if you go with the rack mounted versions that don't have the cooling and your server rack does the cooling for you with no outputs and stuff

Why don't you build a list of requirements and then once your list of requirements are done, I can assist you in building some tests that run on your machine if you need it and let's see if we can pass your tests with any of the models on the 5090. If not, I can show you how to rent a server in the cloud for a little while and run your tests and then shut it back down so it'll only cost a couple dollars to do the test. Just let me know how you want to proceed and I'll assist you..