With that in mind, baseball cards featuring their favorite players or the local team would be a great idea. Many baseball leagues may give these away for free. Check out their websites to see if they have such offers going around.
Children would expect to be able to play some baseball with full gear. While you don’t need to worry about their jerseys, you would like to give those miniature kits which are suitable for the kids’ age. Many websites sell these, even the official websites of major leagues. Check out which are the cheapest ones and go for them. Children do enjoy playing with baseball cards.
However, to get them excited, nothing would be better than posters. Large or medium size posters with the nation’s biggest stars are just what they need to feel good about attending the party. Most major leagues give these posters for birthday parties for free or with a small charge.