AITA for wanting a "designer dog"?

I (f27) and my bf (m28) want to get a dog together. I want to get a dog from a reputable breeder while my boyfriend is very pro- adopt don't shop. I don't think a shelter dog is the right fit for us for a lot of reasons though. I am mildly allergic to dogs, so the dog needs to be hypoallergenic. We want a younger dog/puppy as well and the dog to be small (we live in an apartment). That combination is basically impossible to find at a shelter. My boyfriend has also never had a dog before (while I have had multiple dogs) and I don't think he realizes that shelter dogs often can have issues (that aren't their fault obviously) that takes more time, training and experience than he has.

I also just would prefer to get a purebreed in general. You know what health issues each breed is prone too, especially as good breeders know the dog's heritage and all the health issues that are in that specific line as well. You also know what temperament the dog is prone too. Again, my bf has no dog experience whatsoever so I think its a good idea to get a dog we know will probably have a good temperament. I have a friend who's dog was basically half hunting dog and half Shepard dog, and we think a lot of her behavioral issues came from basically having conflicting instincts.

I know a very good breeder who has all of her certifications. I've been to their house before (my aunt got a dog from them a few years) and its very obvious that the dogs are being well treated there. They only have a litter about once a year (sometimes its even two years) and they announced they're expecting a new litter right now so I think we should put down a deposit on a dog soon because they always are immediately sold out. If we don't get a dog from them now it will probably be a while before we get the opportunity again and this is actually a breeder I trust. My boyfriend thinks that we shouldn't waste money on a "designer dog" but I don't know how to get him to understand that we're NOT going to get the dog we want from a pound.

TLDR: We need a small hypoallergenic dog. My boyfriend thinks we should adopt from a pound while I think that's impossible and we should buy from a good breeder instead

EDIT TO ADD: There are small hypoallergenic dogs in my area, but they are all older. I would be okay with adopting an older dog but my boyfriend doesn't think he can handle only a couple of years with his dog. A lot of the other dogs that fit the bill are very obviously from puppy mills disguised as pounds. Again, we need a dog thats small, has the right temperament for living in an apartment, and doesn't set off my allergies. I love pitbulls, for example, but I don't have the time or space to properly take care of one. I don't want to get a dog that I can't properly take care of. Lastly, I know that all dogs produce dandruff. Hypoallergenic dogs are a great solution for people who have MILD allergies (like I do). I've lived with my aunt, who has a bichon frise (the breed i want) and I had no issues with my allergies.