I can contribute a first hand horror story.
I was hanging out in show crowds, belonged to my local club, read every boxer list for YEARS before I even had a boxer. I wanted to show more than breed, but got a lovely bitch through a coownership with the understanding that we'd have one litter if her health tests panned out.
Well, two holters and other tests later (~500-600) she was bred and had an uneventful pregnancy (extra vet visits, of course). She delivered one pup and then stopped. A couple of hours went by, discussed things with the vet, finally brought her in. C-section. 9 puppies. She died.
So now I have 9 orphan puppies. (And 4 are white, so by ABC rules I can't even sell them!) And a $1200 vet bill for a dog that's not even coming home with us. Plus $ to do a necropsy to see why she died (undetermined -- her heart just slowed until they couldn't get her back). And cremation fee.
Now there's no time to mourn, because 9 puppies need to be fed every 3-4 hours, and it takes 2 hours to do it! I hadn't planned on a vacation -- after all, Mama Dog does most of the work for the first three weeks. I had that covered with my Mom staying and overseeing that portion -- I was going to work shorter hours and shorter weeks later when the pups were more active and demanding.
Well, all that went out the window. Suddenly I was taking a week off with no notice and building incubators at home ($$$). Aside from eating, we had to take the dam's place and clean them as well, stimulating them to go to the bathroom after every feeding (and burping, and cuddling). We had to keep them immaculate to avoid urine scald and infection. They were very picky about which nipple they wanted, and it varied from pup to pup and day to day, so there was lots of stressful effort to feed even one pup.
We did manage to find a foster dam to take 5 of the pups (I had the connections to do that and thank god for them!). She was 90 minutes away. So now we were down to 4 puppies.
I'd say we spent about $500 on milk replacer (even with the foster dam, so count on $1000-1200 without her). Of course it was pretty impossible to grieve - no time and no energy.
And did I mention there was a 4 day heat wave in the upper 90s and we couldn't turn the air conditioning on because of the puppies?

And our washing machine was doing 6 loads/day, and the drainage just wasn't up to it? Friends were bringing us meals and doing dog laundry for us as we sat in a stupor between feedings. And on Saturdays I drove 90 minutes to visit the other pups, stayed for a half hour, cuddled them, and drove 90 minutes back (leaving others to take care of the other pups)
At the three week point, it was time for weaning and the other puppies rejoined us (we never lost a single one, a major victory, actually -- I'd been told to expect to lose several). Then the hard physical labor began, with all the cleaning up. And we were still in mourning.
And then there were the puppy checkups, and microchipping and vaccinations and that was close to ~100/puppy when all was said and done. And did I mention that only 5 of the 9 were able to be sold? And that we were keeping two anyway, so really I only had "income" from 3?
Yes, breeding for fun and profit!