Had to laugh at this. I'd have a strong preference for others subsidizing my questionable decisions too.
1. They are required to raise additional funding for maintenance. I'm not sure I'd bet on them having the same interest in this project in a couple of months
2. The DAO neglects the item, and it gets irrecoverably damaged/destroyed. The ConstituationDAO has now effectively destroyed a copy of the constitution
3. They find themselves in the position of having to firesale the item in a couple of months when they're unable to cover the associated costs.
I'll also add that it would be _possible_ for the DAO to have enough funding after purchasing the item to generate income/returns that can cover the associated costs. Given that their funding is public, and will be participating in an auction, I'm not sure I would bet on having a whole of of funds left over.
For an organisation like a museum, who already have secure climate controlled storage, and are already open to the public, it would cost next to nothing extra to keep it.
Yet merely having a copy of the constitution will get many more people through the doors to buy postcards in the shop and coffee in the cafe. That will far outweigh the added costs.
You lose a lot of negotiating power though when everyone knows that you are going to have a very short deadline, and don't really have an alternative.
It's common for artifacts to go on 'tours' like this, so as many people as possible get a chance to view them.