First, no we weren't able to use existing footings. However, our project had two plusses going for it that your project doesn't.
1) The support locations were not particularly restricted. With yours, you don't have a lot of options for interior supports. I believe ours is supported by 4 supports that are fairly evenly spaced. From the renderings, it looks like yours will only have 2 supports, spread all the way to the edges. This means the supports will have to be bigger, and therefore, construction of the footings and the supports themselves will likely take longer, and should be a slightly more complex process.
2) We didn't have to work on the project during football season. It's much easier to finish a project when you don't have down times where you have to clear out the site for games. With 6 home games, your construction crew will have to divide the work in ways that they complete certain pieces of the project in stages so as to not interfere with gamedays. With ours, the schedule could be set in any fashion, because the construction was not going to be in the way of any activities.
I'd also guess that the actual supports and construction are a big chunk of the cost on your board, which means you are likely getting your video board and sound system for a cheaper rate than what we're paying.