They come in many different types, but any/all of them, including the cheapest available, will probably work for your purposes. The better ones are larger (for big families) and have the ability to keep rice warm without it drying out, so you can just leave it on the counter with rice in it all day. If you aren't a family of Asian people, you probably don't need that.

The features I'd recommend are:

* non-stick
* auto-off

You should be able to get a small one for around $20.