I would bet that you could get your deposit back especially if you plan on reporting the conditions the puppy was in and that you were misled on the breeding situation when you agreed to the sale. (I'm sure the internet picture was taken in the "nice air conditioned house" that the "breeders" enjoy. Then the poor puppy taken back to "the barn."
If you choose to go ahead with this (and they are counting on it to keep this unscrupulous operation going) please plan ahead.
#1 Buy the most comprehensive pet insurance you can get before your puppy starts displaying any health problems. (If these folks offer a health guarantee you might as well use it for compost because they either won't honor it fully, or your puppies health problems won't present until you are hopelessly in love with him. (They will want him back to trade for another, like any of us would do that!)
#2 Start a savings account for behavioral training, as he is likely to have issues that are difficult to live with, such as innappropriate biting/teething, chewing, barking, great difficulty with potty training, etc. Good breeders will often keep their puppies with mom and their other dogs (IN THEIR HOME, NOT IN A BARN) until the age of 10 or 12 weeks. Here, they learn from their parents and siblings what is appropriate behavior.
#3 Puppy farm operations breed without regard to previous inherited health issues in the parents. Mitral Valve Disease (MVD), cataracts and other eye issues, patella and hip problems, as well as skin allergies are passed down from generation to generation and it is very likely that your puppy will suffer from one or more of these ailments at a very young age.
If you are saving a few bucks on this end purchasing this puppy, you will most certainly be spending alot of time and money at your vet's in the end.
I didn't mention chronic tummy ailments and possible ear mites, giardia (oh, you did say he had fleas...another BIG RED FLAG.)....
This is certainly your decision here. If you want to "rescue" a dog, there are many, many older dogs that have been taken from breeding farms such as the one you have visited, that have led wretched lives in barns with no loving families or care. They are desperate for homes.
If you choose to buy this puppy, just walk away with him, be prepared for any or all of the above and good luck!