Not a chance. To begin with, look at the bone structure in the legs, body, etc. Neos are large, heavy boned lugs, not lightweight athletes. LOL
2nd, no reputable breeder would A)Post their puppies on kajiji, or B) charge you $250 bucks for a pup. Molosers are typically poor whelpers, generally requiring c-sections to birth the puppies safely. A breeder can spend upwards of $6-8,000 by the time the bitch has been bred, pups are on the ground, and have gone to their new homes. $250/pup doesn't even begin to cover that cost.
The fact they mention nothing about AKC/CKC registration, or pup being a purebred, or familial lines, means it's most likely a backyard breeder who's thrown 2 dogs together (or they've gotten together of their own accord), with nary a though for genetics, bettering the breed, or breeding "true to type".
If you want a dog from a reputable breeder, check out the Neo Mastiff clubs http://www.neapolitan.org
(U.S.) or http://www.nmcc.ca/index.asp
(Canada), and ask lots of questions! Expect to pay big bucks for a good puppy too (My OEM was $2500, which is the going rate here in Canada). Just remember, don't let the sweet wrinkly face of a puppy blind you when it comes to health, bloodlines, temperament etc. Big dogs = big vet bills!!!
Most of all though, Happy Hunting!!
These are typical 70 day old (or 10 week old) Neo puppies: