Skimmed two of Gilles St. Paul's papers on economics of human cloning:
1. "Economic Aspects of Human Cloning and Reprogenetics,"
2. "The Economics of Human Cloning"
The first is less technical and gives a wider discussion of various issues while the second is more technical and specific.
From the latter paper:
Within an overlapping generations model:
"Young agents have a fixed time endowment, which we normalize to one. We assume that there is a time cost b per child of raising children. People can raise children for themselves or clones of other people, acting as a surrogate mother. ... Therefore, there exists a threshold level of ability, ..., below which agents will entirely specialize in the production of clones, and above which they will entirely specialize in production."
I actually found the assumptions (and conclusions) counterintuitive only because in my mind cloning implies producing a replica of oneself at a pre-selected age e.g. at age 25 so that there isn't any time cost to raising clones.
Guess I've been watching too many bad sci-fi movies.