Here are the con's that I see:
Who pays for it? Since it has been difficult in the past to get everyone to pay their $10 or $20 for something, it seems harder to believe we could have a $1000 project.
If you didn't pay, do you get to play? If people chose not to pay into it that is their right. And we can't limit them from coming to an event. So, foreseeable as an issue, people who didn't or won't pay get the same benefit as the others.
Who owns it? This is a huge issue because that means it has to be accessible to anyone wanting to use it. Which leads to...
If it breaks, who fixes it? If something happens and someone puts it back and says nothing, like humans sometimes do, we could be out a broken piece of equipment. Which leads to...
Where do we store it? It would have to be somewhere secure that everyone or anyone of us would have access to. So if it is in your garage then you have to pony it up if it is needed, whether or not you are trooping.
You charged what? Parades cost money. To run a float in the Starlight FARRRRRRR exceeds our past budget. Again, knowing that we have been screwed and had budged issues in the past with the regular fees, the float fees will be a toughy.
What will pull it? Someone has to volunteer a rig to pull the thing, which is a liability issue, leading to...
Liability? Having this is a liability. It means if someone falls off or is run over by it, the owners are responsible.
Here is where the legion stands, and I firmly stand, on such issues. If you want it, build it. If you want to bring it, ask permission of the member who is running the event. If it breaks that is your deal. If someone is hurt it is your deal. The legion doesn't authorize or sanction these as part of our group. So it is an individuals responsibility, which means if you bring it to an event, you cannot limit a single member from its use or display because you have knowingly brought it to an open event for members.