My wife and I have been rescuing dogs for over 50 years.
From the shelter, from the side of the road.
We've had as many as 8 at one time before, that got down to one and then built back up to four at present. That's about all we can afford, being seniors on Social Security. Our veterinarian has very reasonable prices, but still 4 is all we can take care of.
When we adopt from the shelter, we choose older dogs, preferably 10 years or more. We look for dogs that have been passed by for a long time, also sick dogs.
The last two we adopted were heartworm positive, our county shelter provides all medication for free, and when they test heartworm free the adoption fee is waived.
Right now we have a full blood Black Lab, a Tri Color Hound, a mix of short haired Pointer and Tri Color, and a sweet little Dachshund/something (?) mix.
The 65 pound Lab is my lap dog.