Get it for him after he is at his first duty station. Chances are that regulations will keep him from carrying it during his initial training, anyhow. Besides, you don't really know the morals of the people you train with. There is a good chance that someone will try to "borrow" his knife. It happened to me during basic in the 1970's. I did get my knife back after I threatened to wrap a M16 barrel around the neck of the punk that took mine.
Also, I would not buy a knife that is anywhere near that much money. A nice Alox SAK and maybe some sort of Cold Steel should work just fine. An Emerson CQC 7 of some sort would also be nice. All three would not come to anywhere near that amount of cash.
Give your friend a chance to find out what he can legally carry on base, if anything. The military has gotten a lot more PC than when I was in.