Why not just buy your club some balls... Some el-cheapo training balls on Aliexpress cost 20$ per 100. Are they crap? Yeah! Do they do the job in multiball training also Yeah! 20$ is not that much, it's about half of what I pay to play in my club per month. (my club has balls though...) Its one-time purchase, not that big of a cost. If you step on one. Not that bad, you still git 99 of them. Mine have a year or two of training after them, still got 80-90 of them, all of them are fine, although they are a bit on the easy to damage side. When it comes to balls flying to other courts ball catch net is a must. When I was training with my friend, we rented a squash court with a table tennis table and we gathered balls by hand. Feeding balls isn't fun, but it gives you time to recover. I suggest training in groups of 3, one feeds, one rests, one swing (and then change ofc).
PS: At the club where I train we use Panda training balls. They are better then Huieson, but more expensive. Good compromise if you need lot of them.
