Taking care of 2 Kittens

4 months ago, there was a mother and maybe 5-6 new born kittens left outside in a box. My friend had taken the box with the mother & kittens and had called me over to tell me what she had found. She asked for my help in trying to figure out what to do with them. I had a cat a log time ago so I had an idea of what to feed the mother, but not the kittens, I had no idea of how to take care of them. So, she asked me to look after 2 of them, while she looked around to see if others would take the other kittens. I never realized just how much work & money it takes to take care of kittens. Feeding them kitten milk(expensive) thru a syringe, etc. Bottom line, I want to keep these 2 kittens, but financially they have already taken a big chunk of money out of my wallet, due to going back & forth to vets, food, medicine, etc. I can't keep taking money(that I don't have) to maintain them. I maxed out 1 of my credit cards taking them to vets. I am trying to save up money so when I have to go to the vet, get medicine, etc for the kittens, I will already have the financial means. I have been postponing some of the vet exams because I don't have the money. Soon, I will have to get then spayed/neuter & I'm worried about getting it done on time because financially I don't have the money. I was supposed to help them until they were out of the kitten stages & then find a home for them, but I am in love with them. There is no way I can give them up. They are now my babies. Please, any help will be greatly appreciated.