I started with a couple 6-packs of Creeping Thyme and then started transplanting. But now (4 years in) it has literally taken over my yard - I am pulling Thyme up and feeding it to the garbage can. This stuff could become invasive. But its so pretty!
Also, growing amongst other plants (not just pavers), is fine with me - my gardening style is pretty haphazard.
I have heard (on this site) others saying it grows from seed.