Finaly got fed up with my pet store

Tell the other shop you'll give them a whole litter at 4 weeks that they can sell and pay you for after they're sold.

Tell them you want 1.50 if you consign them and 1.00 if they buy them outright. Give them the first batch to get started with without paying up front though.

I've done it with shops and it works pretty well. They see they have a market for pets as well as feeders. Pets mean toys and vitamins and special bedding and more profit. Feeders mean they don't keep them long and customers return week after week. Point these things out to the store owner.