I would not decide on caliber based on the Great Ammunition Panic of 2013. IMO, either buyers will run out of money, or someone will crank up more production. Either way, supply will eventually catch up with demand.
That said, now that I realize you're in CA and have a 10 round limit, I would look much harder at either 9mm or .45, and I'd skip .40. This is entirely a matter of opinion, and it's worth exactly what you've paid me for it. I'd look at the purpose of the pistol:
Targets -- 9mm for ammo costs. It's hard to find right now, but that will not always be the case.
HD/SD -- .45 acp. Please don't misunderstand me. 9mm is a capable SD round. However, if I'm going to be limited to 10 rounds, I'd rather carry 10 rounds of .45 than 10 of 9mm.
I'm a lawyer, but I'm not your lawyer. If you need some honest-to-goodness legal advice, go buy some.