Putting this in a separate building instead of renovating a room in your house creates some major cost.
A separate structure will require power and HVAC and unless you fancy running through the cold when you need to pee it'll require plumbing too.
HVAC is a tricky beast. You have to control both temperature and humidity. You can hack together temperature control with cheap window units but if you want humidity control so you're not wet in the summer and sick (because of the dryness) in the winter you'll need real (expensive) HVAC.
Power is a fiddly beast too. You're not just running an outlet here, you're feeding a subpanel.
You're not erecting a shed here. You're in to at least a few tens of thousands of dollars. Just how generous is your new employer?