In my opinion, it depends on your town demographics. I'm currently in a small somewhat affluent town that cares way too much about sports and probably has too much town pride. So people love to support the teams. If you are in that kind of town, find something to sell, but it's not even important what it is. The key is to get the kids and their parents to inundate town-based social media with the sob story. Put up pics of the crappy equipment. Engage all town groups you can find, and really focus on youth programs. Our high school soccer team sold a lot of stuff to our town-based club.
Speaking of youth programs, see if that program wants to help you guys out. If they have fund raisers they probably won't want you to steal their thunder, but "experiences" can be cool. Batting practice with the team. Bat boy for a game. You and your team guest-coach their games, etc. Split the proceeds with the program. If you can get that into an auction where people are drinking you could make a ton.
While I said the "what" may not be the most important aspect, it does help. People often have town-pride, but it's not always easy to show it. Think of all the UConn gear you probably have/had, but how hard it is to get nice stuff from your town. Get some quality stuff to sell. Emphasize the town over the "baseball" when possible. Tshirts, sweatshirts, blankets, umbrellas, water bottles, fleece pajama bottoms are big. Town colors seem to sell better than random colors.
If you're in a bigger town that is a bit more economically challenged, go after the businesses in town or even in nearby towns. Small businesses may be happy to help to be part of the community, and big businesses love trying to show they have a heart, especially if they can be seen as giving kids a chance to succeed.