I do not want this to sound cold and unfeeling toward the little one, but do you think that you could negotiate with the seller? A lower price now or a deposit with a receipt to hold him until June? I suppose if the child is allergic they would want him out right away. A family member who would spot you the money for a couple of months? Just wondered.
I also wonder why they want so much for him. Is he registered? Have they paid for neuter, medical expenses?
Just a questions... if you can't afford to buy him, will you be able to pay for all the vet bills that come with a puppy? Just something to think of since you already have a pack going already It gets so expensive!
Of course it would make a difference if that amount you were paying for included him already being neutered/having shots/etc. Is he all up to date?