Did they give you $5000 as a quote for having all the molars extracted? Once they are under anesthesia- yes, it will cost more to pull more teeth and he will need to be under anesthesia longer- but it would still be cheaper than separate surgeries.
Since this is the first time- even though he is young it would not be a bad idea to see what happens and how this progresses. Maybe, just maybe this will resolve with an initial treatment.
Unfortuntaly I doubt insurance would cover the surgery even if you had insurance all along- the fact the doctors think Buzz’s jawbones did not properly form makes me think they might rule this out as a genetic condition. (VPI does not cover genetic conditions like hip dysplasia in dogs and malocclusion in rabbits).
It varies from state to state so it is always a good idea to check with the insurance company if you have any questions.
Did you get Buzz from a breeder? If so- you should notify the breeder. Even though I am sure a breeder would do nothing to help Buzz- they should at least KNOW what resulted from their breeding practices.