As mentioned in a previous post growing plants from seed will save you money and will give you a chance to grow varieties that are not available to buy in the garden center. Soil blocks are an alternative type of container used for starting seeds. In fact container is a misnomer because the soil block has no container, but is a soil mixture that can hold together in a block. This has the advantage that you can transplant directly into the garden and there is nothing to restrict root growth. This information comes from Stephanie Rose on her Garden Therapy website and is part of her series on seed starting.
You can read her article at Garden Therapy