Why not create your own nutrient rich compost using your kitchen and garden waste. You will be helping to reduce, reuse, and recycle, and you can save money on buying compost. A wormery is also a good way to create compost, and is ideal for small houses and flats.
Getcomposting.com has a useful guide to composting.
Buy a composting bin
You can buy composts bins from the following places: