I have to agree with sigarms228 on this one. The 229 is a great handgun and if you can talk yourself into a 40s&w instead of 9mm all you would have to do is get a 357sig barrel (or vise versa get it in 357sig first and 40s&w later) for it you can even use the same mags for both calibers. It seems like one of the most cost effective ways ammunition wise to go about your situation in my own opinion.
I agree that the P229 is a great handgun, but I think the 9mm is a far better round for a new shooter than a .357 SIG or even a .40 S&W. And instead of having to buy conversion barrels, he can just spend that money on ammo and maybe even training.