I bought my original group from a guy who bought from a "breeder" that made him sign papers.
He fell on hard times and passed them off to me, I didn't sign papers so I bred them and have been for several years.
The original group of 14 rats cost just over $400 and included genetics to produce blue, Black red and ruby eyed Siamese, dwarfs, and other traits.
They came with paperwork showing 5 to 7 generations back and what they produced, well worth the initial large payment considering the quality of genetics involved.