SIM cards are carrier-specific, not manufacturer-specific. If you buy a phone from a GSM carrier (CDMA phones don't use SIM cards for 2G connection), you get a SIM card from that carrier. If you buy a generic GSM phone (from the manufacturer or a wholesaler), you don't get a SIM card unless you're also buying a plan from a specific carrier.
(It's not really something to worry about, though. When they charge you $5 for a SIM card, about $4.75 of that is for the clerk's time in selling it to you - the cards are worth a few cents. If you sign up for a plan using your own phone, most dealers will give you the card for free.)