Best as in very selectively bred for many generations before I purchased them.
When my partner and I bought our original group of 14 rats it cost us $440 and every rat came with 5-7 generations of pairings so we knew pretty munch what each rat would produce.
The genetic we got included: All dumbo eared, some velveteen and some rec coats, black eyed Siamese that carried red eye recessives, Russian blue, American blue, black eyed whites, blue agouti, manx, dwarf and a few others.
Would I recommend paying $70 for the average breeder to make feeders, not at all.
I did what I did to make pets to sell to pay for the whole rat breeding operation and it did that and then some selling pet rats 2 for $15.