So many used parts become available when one of us gets a new chair. And these companies know EXACTLY what parts will be most necessary. This is purely a matter of $$$. Our gear isn't like a sofa or even a TV or laptop. It's life altering. A delay of even a day can be catastrophic/life and death.
And having a state university's legal department behind you when you tell the vendor "We can and will sue you for $25K per every day the ship is tied to the pier while we're waiting, OR you can cough up the correct off-the-shelf part #. Your choice." is definitely handy
Regrettably, I had no university behind me.
Yeah, I know, not quite the same situation.
We need money to throw at disability issues. And better policy! When I graduated college still needing attendant care (1992), I could not work, because $1000 mo bad would knock me off Medicaid, and then I couldn't pay the person who dressed me. No graduated income, just a flat cut off.
Believe me, I understand. I have rebuilt a couple of chairs for family/friends