Check with your boss/HR. My partner works for a University, and they have received an ergo mouse, chair, and motorized adjustable desk for their home office simply by requesting them. Most organizations have a budget for IT accomodations and they hardly ever use it.

Also, if you can get a Dr’s note for it, most places will purchase just about any accomodations you need for work. Larger monitors, ergo keyboard, dictation software…etc…