There is a saying, 2 puppies together are not twice the work, they are three times the work. My maths isn't good enough to work out how much extra 4 is!
I would not recommend selling them unless you are an experienced breeder because they are vulnerable to people buying them for the wrong reasons. A life as a puppy farm dog is not a nice one, and puppy farmers can be VERY convincing in the way they hold of their breeding dogs.
If I was in your situation I would give them to a rescue centre who home checks and has lifetime back up for the dogs. I know it's not as much money but this is about lives, not pockets.
Good luck.