I re-bought everything, chair, monitor stand, electronically raising desk, keyboard, two vertical mice - for left hand and right hand. I didn't find it that hard to use a left handed mouse as a right handed person but your mileage may vary. I swap between the two throughout the day.

I think out of all of those, having the monitor at the right height, vertical mouse, kinesis advantage and then using a pomodoro timer are the best bang for buck. The standing desk is nice but not really essential in my opinion. Just getting up and walking after a 25-30m pomodoro session is good enough.