Since your list of questions seems to have been answered point by point, I'll take a different tack.
How much to pay? The purchase price regardless of cost will be only a small percentage of what you should expect to put out caring for your dog over its lifetime.
You may be able to buy a Boxer for less than an adoption fee, but there are several things you need to consider, other than price shopping.
If you buy from a back yard breeder, or pet store, you are more likely to end up with a dog having health issues than if you buy from a responsible breeder. There are always exceptions to any rule, and you may end up with a healthy dog that lives a long healthy life that came from a puppy mill. It's just that you aren't likely to.
In addition to cancer and heart problems, Boxers are notorious for allergies. Responsible breeders don't breed dogs with known health problems. Backyard breeders don't do the testing necessary to breed dogs whose hearts are free from detectable problems. Puppy mills don't know and don't care. They are strictly production line, they only care about the dollar.
Yes, a responsible breeder may ask a healthy fee sometimes far exceeding a pet shop price. They do this for at least two reasons.
First, it costs them a lot more to produce a litter of puppies. The cost of health testing can be staggering. Secondly, and perhaps even more important to them is it tends to weed out all but the serious puppy hunters, and it gives them an idea of whether you will be serious about tending to your dogs needs.
We got our first boxer, Rocky, for free. Our daughter worked in a pet store and he had a heart murmur which did disappear as he grew. But he was plagued with all manner of allergies, and it is heartbreaking to see one you care so much about being plagued with these problems.
His weren't a severe as some dogs, but he did require special food and we had benadry and a prescription med on hand for the reactions the benadryl didn't touch.
He had to be euthanized at eight and a half years of age because of cancer. In the last week of life, we put out almost $6,000 in tests and care, in the hope that he might be treatable.
I know that not everyone can go that far, but we could and did because he meant that much to us. It kind of makes the freebie price not so free. Factor in the extra visits to the vet for his allegies and from a fiscal standpoint, free was no bargain.
Add in all the other expenses such as regular vet visits, feeding, toys, and miscellaneous items, and the initial cost becomes a drop in the bucket.
The most important thing for you to consider about Boxers is that they are part of your family. If you wouldn't make your child sleep out in the cold, you don't do it to them.
They will thrive, and reward you beyond your wildest expectations if you put out the effort and concern to bring it out of them.
They don't like being separated from their family. They are at their best when they can be in your presence. This is the single most important thing to a Boxer, is being with you, frequently underfoot.
They don't expect your attention, they practically demand it.
They are great with kids, and generally speaking, they are great with just about everyone. Like any breed there are some that don't quite fit the mold and can have "emotional" problems.
That is another reason for going to a responsible breeder. They can predict with amazing accuracy the personalities of each puppy. You won't get that from a BYB or a pet store.
The responsible breeder will prove to be an invaluable resource for you in all aspects of your dogs life, and enjoy keeping up with each of their pups. Yes, even though you may have possessionl, they still consider them to be theirs.
The Boxer is suited for all the requirements that you listed. The question is, are you prepared to accept the responsibilities that come with having one? This is a question all of us have had to answer, especially when getting the first.
Most dogs are fine. It is us that are responsible for most of the problems.
Tom