Just checked out Layne Labs VS Rodent Pro.

100 small rats.

Layne Labs $111.00/Rats $47.70/Shipping 19 to 28 days old, 40 grams and up, 4-5/8" long

Rodent Pro Currently on special $79.00/Rats, Regularily $99.00/Rats $42.28/Shipping, 26 to 32 days old, 45 to 84 grams, 4-1/2 to 6"