I think I forgot to follow up on your question...you may already be aware, but BYC has a swap thread. When I was looking for my first broody hen, I went to the swap threads, found a local swap listed that was in my area, and by connecting up with people on that, found someone willing to sell me their Silkie who was a good broody.
You might connect with Silkie people...twice now I've been able to locate someone with a proven Silkie broody who is re-homing her as she no longer fits into their breeding program. Silkies are a very broody breed, so I think the breeders tend to get too many broodies and are more willing to part with them. You might want to get two or more to work with the larger Malines....sisters, or mother and daughter, pairs often will co-brood together.
Ditto with bantam Cochins...they spread even better, and are a popular breed with 4-Hers so there may be a more available market.
I've wanted a full size Cochin, but have had trouble connecting with breeders for that one.
Good luck find another broody.
Lady of McCamley