As an aside...my friend just lost her bitch yesterday in whelp. This was a healthy Swissie - her 3rd litter I believe - she was five. My friend is a vet tech in a reproductive specialty clinic - she's also on the c-section team. Labor began and then an hour later there was the tell-tale green discharge. She rushed her to her clinic - 30 minutes later she was on the table - as they were getting puppies delivered her heart stopped - just stopped - and they weren't able to get her back. Turns out there were two puppies side by side in the birth canal and they think that removing the pressure from the full uterus put her into shock...anyhow my friend lost her CH bitch - lovely lovely dog and four of the ten puppies. She was lucky enough to find a lab that had delivered yesterday as well - a singleton - and she stepped up as a foster mom to the surviving puppies. She is an experienced, educated vet tech...and she was powerless to save her girl...You ask what can it cost? How about it can cost you your dog's LIFE! Is that a cost you are willing to pay?
Wait till you are ready to breed her to find a mentor? Do it NOW and learn all you can long before you even think about breeding her.
Has the dog been check for genetic problems (clearances)? And I am not talking about your vet saying she is healthy enough to breed, that is NOT good enough.
Every time I hear someone talk about breeding for just one puppy I cringe and think of that kind of scenerio...Can you stomach the heartbreak?