For example, one could use those nearly indestructible rubber baseballs--they're very cheap and you won't feel bad even if you knock it so far it gets lost. Or bats--you don't have to use aluminum bats; locally made wooden ones are also fine.
用不易打破的橡皮軟球，非常便宜，即使打飛了也不會心疼；球棒也不一定要用鋁棒，國產的木棒也很好啊。