I did something similar. I had a farmer friend bring me three calves, one was not doing very well at all was 3 days old and pretty much refused to drink. I was able to keep that one going for approx a week and then it died. What we did with the other two was I got the heifer calf and he got the bull calf back. He had bought the milk replacer and provided a bale of hay (round bale)for them once they were older. I bottlefed as I did not have any cows or anything, but it worked out great, as I traded the heifer back to him for a young cow to butcher. It worked out great, but I think you would want to have some sort of agreement drawn up if you weren't good friends.