Another problem you might face if you buy your kitchen island as a separate unit, and not as part of the overall kitchen, is matching it to your existing cabinets. This might not be as easy as your think, but if you purchase a solid color, such as black, white or red, then you should get away with it.
If you have doubts, you could always ask a professional designer to go over your kitchen space and make a recommendation or, if you want to save money, you could visit friends who have a kitchen islands and make the necessary comparison. Moreover, you can choose for your kitchen island to be in an L, U, or a G shape.
Take the opportunity to make your kitchen island mutli-functional because there's lots of options to choose from. Just about any appliance can be built into it including cook tops, under-the-counter refrigerators, sinks, dishwashers and trash compactors. Deep drawers provide a place to store bulky cookware and pullout shelves allow for more easy access.
A second kitchen sink can be included on the kitchen island. Use a sink that is deep enough for washing large pots and pans, and consider equipping the kitchen island with a trash compactor, garbage disposal, recycle bin and even a dishwasher. Cleanup will be much easier when these appliances are close by the sink.