The SMD bulbs that you are talking about uses the LED which are used in LED strips. These don't require any heat sink.
I have seen your LED light project on an other website. You have used LED drivers there. What if we don't use any driver and connect 4 nos of 1W LED in a series and connect it to 12V.
BTW what is the price of 1W LED in our city.
you are right that the smd leds are same as the ones used in Led strips. part number is 3528. there is better version called 5050. unfortunately, my research indicates that such ready made led 'bulbs' last only a few months. the rule in led is, If no heatsink- STAY AWAY!
I guess you are talking about by Led headlights?
the Led is have used are very high quality and costly. they can be driven upto 5w per piece. as an headlight will be on for long duration, it was wise to invest in Led driver for reliablity and longer life.
you MAY connect a series of 4pc 1w power led directly to 13v supply, but better test them with your multi meter that they are not drawing more than 300ma . a heatsink will be MUST with any currents larger than 100ma
use resistors to bring them to about 300ma If they're drawing more.
cost for Chinese ones is 25-30 per piece. buy ones with star board.
cost for USA (cree ) or Seoul is about 500 to 750 rupees.