Need advice on helping an injured feral kitten
So me and my husband have recently discovered there is a momma cat with 3-4 kittens (maybe 4-6 weeks old?) living under our shed in our backyard. We have been trying to help where we can, putting water and affordable wet food out for all of them. Unfortunately we saw today that one of them has an injured front paw or leg. The kitten is putting no pressure on it, just limping around with it raised. We are unsure of what to do cause they are extremely skiddish around us and run and hide underneath the shed as soon as we come out and even if we did catch him/her we couldn't afford a vet bill.
I've looked into rescues around us but don't see anything really that would help and we've been through this before 2 years ago when we found a sick kitten in our front yard and took him to a vet, paid nearly 400 bucks to care for him and actually ended up keeping him after I couldn't find help anywhere (best decision we ever made) but we just don't have the money for that this time around.
We live the Vass/Lakeview area in North Carolina. It's also been very hot out, is there anything we can do other than putting out water and food for them.