We erected an 80x90 indoor facility about 12 years ago and I would give you this piece of advice. Make sure you have all (or the large part) of the money needed available before beginning the project.
Our booster club raised about $25,000 and we were able pour a slab, pay for plumbing and buy the metal building that we erected ourselves. But that tapped the account out. The two dads who were ramrods of the project had sons graduate, and I was left with this shell of a building with a couple of cages inside. It was nice to have, but not what we had in mind with the original plan/vision.
I consider myself a good fundraiser, but with trying to fund my own program and finish the indoor...it was slow going to say the least.
Luckily, the school (good superintendants!!) finished the indoor for us in three phases. Not something I would count on in most cases.
Incidentally, we raised over 10K with an auction held in the baseball parking lot. It involved members of the b. club getting items donated from around town, bringing "flea-market" type items from home, and taking items/equipment on consignment. One of our dads was an auctioneer and volunteered his services for the day.