Where can I get a Verizon SIM card?

Well, you are in black actually and you have given wrong information. Verizon wireless does not make use of SIM cards. They are a providing CDMA delivery service same as sprint only. The only main service providers that use SIM cards in the US are both AT&T, and T Mobile.

The antenna inside the phone finds the towers, not a SIM card. AT&T and T-mobile use the GSM network which has the SIM activating the phone. Verizon's Blackberry 8830 has a SIM card slot in the back because it can work of the GSM network too. I don't know if it can be unlocked though.

All GSM phones and most iDEN phones apply SIM cards. CDMA, TDMA, and AMPS (analog) phones usually don’t use SIM cards. The info is in its place programmed straight into the phone. Though, some CDMA phones for China and Latin America utilize a very similar type of card called R-UIM.

I hope now you are aware with the fact.

Best of luck!