The link didn't take me to an ad, but if this is a puppy from a "breeder" and not a rehoming case, then I would strongly suggest not buying it from them. I'd recommend doing some research on breeder ethics. kijiji is a lot like Craigslist and full of BYBers.
Anyways, ethics aside, be prepared for some vet bills. The puppies from that mix could have any of the health problems that the two breeds have, and since it is extremely unlikely either of the parents had any sort of health screenings done, then your chances are pretty high you'll have medical issues with him. Not to mention the huge size range between an English Bulldog and a pug--I wouldn't be surprised if along with looking a bit awkward, it had some joint/muscularskeletal issues.
So English Bulldogs are notorious for health problems, and a lot of them are genetic. Heart murmurs, cancer, heat stroke/sensitivity, hip dysplasia, mange, dermatitis, cherry eye, hypothyroidism, distichiastis, heart disease, allergies, entropion, breathing problems, luxating patellas, etc. If you go to the Bulldog Club of America, there is some information on those and the proper screening/certification organizations. Here's another link: Learn about English Bulldog diseases
Pugs are prone to have dermatitis, breathing problems, heat sensitivity, luxating patellas, Pug Dog Encephalitis (fatal), heart disease, hip dysplasia, eyes (pigmentary keratitis, dry eyes, distichia, ulcers, entropion, proptosis), epilepsy, nerve degeneration, etc. Here's a link for info: Pug Dog Club of America
and Learn about Pug diseases
As you can see, there are a lot of issues to be concerned about with either breed. Since both are wrinkly and short nosed, I'd definitely be prepared for breathing issues, heat sensitivity, dermatitis, and eye problems/diseases. I've seen a lot of pugs with heart murmurs, so that's a good possibility with the mix. And I'd wouldn't be surprised if he was dysplastic and/or had luxating patellas....
They say the purchase price of a pet is one of the smallest expenses of owning a pet--and I don't think that could be much more true than in this case.