In all my dealings with breeders they have expected the full payment of the puppy at the time of the purchase. I know some are willing to work something out, especially with people they know or trust (already have a history of good ownership and training/titling their dogs), but my expectation is to pay the full price up front and would not hold it against a breeder if they didn't want to take payment plans or options other than cash up front.
I'm not sure how much of a concern the military thing is, but I do know that if it's a good breeder, often there are reasons for the concern/hesitation. You may be different, but just be sensitive to the fact that they've most likely had some bad experiences in the past if there are reasons they won't sell to certain families/situations.
Ultimately the puppies are theirs to sell to whom they chose. I would actually be more concerned about a breeder not caring at all what the person planned to do with the dog or how they were going to pay for it and just selling a dog to any person with the cash.
Coke (All-American 7/7/06)
Nikon (GSD 9/7/08)
Indy (All-American 5/10/12)
Legend (GSD 10/22/13)
Rainbow Bridge Kenya (GSD)