The first time I raised orphaned kittens, I discovered that the small nursing bottles available at vet clinics were too big. The kittens couldn't get their mouths around the nipples. So, at first, for newborn kittens, I used an eyedropper. As the kittens grew bigger, a syringe worked very well, the kind of syringe for giving injections (without the needle of course!). I started out with the 3 cc size and used larger syringes when the kittens grew bigger. The tip of a syringe is about the size of a cat's nipple, and my kittens eventually sucked hard enough on the end of the syringe to draw the plunger down by themselves. Check with your vet clinic to see if any used syringes are available or to see if you can buy new syringes from the clinic.
Munchkin Kittens to adopt