I used Scott's grandfather's table top he made and put two wooden boxes I had gotten on clearance from Target as the base. That is a story in itself! Oak is heavy and a circle is really awkward to get up the stairs from my basement! I love that I took the island out (now in the mudroom, where it is just as handy for storage.
Extra tip - I hated my trash sitting out by the island in the middle of the kitchen, but my pipe config under the sink was too weird to put in a standard waste basket. I sat and looked and looked at it and wah-la - a 5 gal rubbermaid tote would just fit if I did some creative hack-saw work on the sides and on one of the handles. I am still lovin' the openness 1 week later!!