He's got that face...Lady had that face. she was so unhappy about being so small.
look at those paws too. he's going to be a big boy. i'd get him too.
and the bow tie...no white streak that a lot of rotts get. the breeders like to send those home with people looking for pets since they don't rate well in the ring.
call this person and ask a ton of questions.
find out if at least one parent is there to see and what about health history in the family and what tests have been done, what vaccinations already, how old is he, can you see his pedigree, will you have limited registration papers (unless you're buying the pedigree and will be allowed to show and breed him), ask that person about his breed standard and whatever else. if you get a lot of good answers, it's a good healthy pup. if this person says UUUUMMMM and I don't know you'll know you're getting a puppy from someone with 2 rotts that did it.
in that case, beware...you may have health issues to deal with in the course of his life.
don't be shy. you're dishing out a lot of money...you want to be sure.