Reply to Josie: I've never bought worms for angling, so don't know how much they would cost, or how many would be needed.
Anyway, the worms used by anglers are exactly the same worms that we use for composting.
Provided you can supply regular kitchen waste like potato and carrot peelings, banana skins, uncooked veg waste, crushed egg shells, etc (you'll get full instructions with any bin you buy), then why not invest in a worm bin. However, by regularly taking out worms you'll gradually reduce the worm population in your bin. Provided you aren't too greedy you should be OK.
Do let fellow bloggers know how you get on.