We've had them for about six months. They're contageous, too. At least to a certain type of person.
These quiet garden helpers hang out inconspicuosly in the front yard on what is supposed to be a dining table that gets mostly gardening use. There is no smell and they really need very little attentions. Every couple weeks I empty out the bottom drain and feed my plants safe, natural liquid fertlizer.
It can be fairly inexpensive depending on the set up you choose -and there are many and varied to pick from - but be sure to remember the make and model if you need to expand your set up. I found our set up on sale with free shipping, I think it was somewhere around $70. I added a few more bins later on (that's why it's helpful to remember the brand/type you bought!). The worms proliferate all on their own after your first batch. If you end up with too many you can help a neighbor set up their own wormery or use them for bait. It's a great way to make your own organic fertilizer, dispose of scraps and maybe even throw in a homeschooling lesson.
If I've piqued your interest in starting your own worm farm here are some helpful links:
http://www.redwigglerworms.com/
http://www.finegardening.com/how-to/articles/worm-composting.aspx
http://www.amazon.com/Tray-Compost-System-Factory-Terracotta/dp/B000S6LZCS
http://www.savvygardener.com/Features/worm_composting.html