It is certainly true that there are educational opportunities that are expensive: special programs, summer camps, supplies and equipment that you could buy, etc.
But there's a lot of educational opportunity that costs very little. One of the best ways to learn anything remains, "read a book". Books are not all that expensive, and you can get many for free from a library.
Yes, it is often good if reading can be supplemented by doing. But many science experiments, for example, can be done using reasonably common household items. Yes, if the child's interest is nuclear physics, you probably can't afford to buy him a nuclear reactor or a particle accelerator. But there are lots of physics experiments you can do with balls and string and springs and so on.
I home-schooled my kids off and on and we got textbooks geared to homeschoolers that often included discussions of science experiments that could be done using fairly cheap materials. I suggest you look into books or web sites that discuss "experiments you can do at home". You might look into resources for homeschoolers, but the issue is certainly not limited to homeschoolers.
Aparente001 mentioned holding fund-raisers. You may be able to get the kids to sell candy bars or magazine subscriptions or whatever to raise money for supplies and equipment.
You could try asking for donations of old equipment from area businesses likely to have the sort of equipment you need. To give them a tax write-off you'd have to create a charitable organization (or join yourself to an existing one). It's a little work but, etc.
You spoke of "families", plural. If there's a group, perhaps they can share expenses. Like if one family can't afford to buy that $500 robot kit, maybe 10 families could each manage to put up $50 and then share it. You'd have to work out an arrangement that's fair to everyone, but it's likely that a lot of the equipment you would want is not the sort of thing that the child will use every waking moment for years. Often we need equipment for one lesson that lasts perhaps a few weeks, and then it sits on a shelf for years.