it has an internal oscillator and dividers, if you read the thread i gave you teh link until last, you can see the diagram.
it uses a 3.2768 MHz crystal osciallator, you still can use 3.2768 KHz crystal if the accuracy is not so critical (may get fraction of a second/day variation).
ecconomical issue is depends on the need, if you want to make 100s of the same then you have to optimise manything, but if its only for a unit, it will cost less than 5$ for the components.