This is a great lesson. People only fix problems when it affects them directly. If you are sitting in a better chair and a developer says that his chair doesn't suit him, you will take it as whining. After all, there is nothing wrong with your chair.
However if you are sitting in the same chairs, you will experience what it is like. After a few weeks, you may realise that these chairs are horrible for your back.
I lived in Kenya before where the roads are terrible and full of potholes. To avoid this problem, the President had special shock absorbers installed on his limousine. After all, he is President. He must deserve it and splurge on himself. Now when he goes anywhere he doesn't experience the same things others do. Since there is now no problem for him, there is no incentive for him to fix the roads.
Don't be a leader who only solves his own problems.
I just tracked you down on LinkedIn (we're only 3 hops away!). This is your first company. I'm not on my first company. Let me spare you a lesson I am still gradually learning the hard way: whatever day-to-day pains and frustrations your team is dealing with, you should be sharing.
Take the extra money for the Aeron chair and buy a couple of six packs for the office. I may have just saved you several tens of thousands of dollars with that bit of advice.