Do not buy online. There was a setup here in Iowa, where they were claiming to be a rescue, and selling dogs to wealthy Chiburb people for thousands of dollars. The dogs were actually from puppy mills. They got some jail time for that, but the mills that were involved are still operating.
Some chain stores charge so much they will FINANCE your pet, again thousands and thousands of dollars and often puppy mill origins.
Go to a local rescue, there are boatloads of them and all those dogs/cats need homes.
GF & I are involved in this doing medical fostering for the shelters. We've had a fell terrier who had nearly fatal diabetes because his owner was a stoner, a cat that was flat out neglected to almost death in a semi-hoarding situation, and now a little affie who got run over by a truck, had to have tail/spine surgery, and will have to have a rear leg amputated soon. And is absolutely the sweetest little dog you have ever met.
My point is that shelter pets are often the sweetest and most loving ones you will ever find. People seem to think they are defective somehow, but that has been the exact opposite of my experience.
Here is a list of very well run rescues, mostly in eastern Iowa:
CC Rescue Partners