I got away with just half an egg shells worth from the juiciest areas of my outdoor compost bin.

Now I figure I'm up to a small grapefruits worth after giving away half a few times.

You can start with 1/2 pound if you are willing to wait an extra 3 months or so for your bin to get to full production.

You may also want to consider the link below. Bentley may not be shipping until Spring, but you can always email him and ask.

Here is a link that might be useful: worm composting kit

Why not dig them up in at least a 2 year old aged manure pile at a horse farm. Most farmers will let you if you ask. All you need is a pitch fork,pail,rubber gloves and boots. I did that and hit the motherload of worms.They are usually found around the edges in the moist stuff.
Might have to wait until spring but it's worth a try.

Good idea to find a free local source and start small, with maybe a quart of compost plus worms from an active bin.

Elementary schools and community centers often have demonstration bins or know of worm composters in your area. Also check with gardening groups or gardening extension agents from your local college or university.