We have a recipe for baby bunny milk which uses mostly kitchen ingredients. It's here somewhere, I'll go find it.
Okay, I found it. Didja miss me? Here's the recipe:
2 cups of 2% milk
2 egg yolks
2 Tbsp powdered milk
2 Tbsp. corn syrup
1 tsp. bone meal
Considering baby bunnies maybe eat a tablespoon full of milk, I usually make this up as a half recipe. And usually use the whole egg since it's easier. And use molasses instead of corn syrup. Most corn syrup is high fructose corn syrup and probably made from GMO corn so we don't keep any in the house. The bone meal can be found in the garden section of many hardware stores and it's shelf stable so it's easy to keep on hand.
I first tried with a small syringe with the needle removed. Didn't work all that well. An eye dropper worked much better so now we use that when we have to feed baby bunnies. The main thing is to not get any milk up their nose. At all. Not any. End of baby bunny when that happens. At least, for the really young ones.