A chair can sometimes make TIG welding easier, MIG too. Long ago an old guy told me the Number One Rule of torch cutting and welding is, ALWAYS BE COMFORTABLE.
Two places I cannot obey that rule is trying to TIG weld on my knees and on a ladder while using the foot control. O, one other place, bottom of a too small, muddy, bell hole, with my feet higher than my upper body, and about eight inches between a rock bottom and the bottom of a pipe that will be X-rayed. It's a tie-in too, not aligned good, and the fit is real bad. Raining a little too. And the other side of the pipe has to be welded left handed because not enough room to lay on your right side.
It might be worth $900 if you could make that weld in a chair.