I picked up one of my dogs from the Lost Dogs Home. I can't recall the amount, but it wasn't too bad. They also desex all dogs.
In general, to avoid hereditary problems, go with mixed breed dogs. A lot tougher due to not being inbred.
If the dog is going to be alone for most of the day, consider getting 2 then. They keep each other company, and are more sociable.
Hope that helps.