Most of the cheap rice cookers (like the one I have) can only cook different types of white rice. In general white rices all take about the same time to cook and take about the same amount of water. The rice cooker I have determines the amount of time it cooks by weight. For instance if you put a cup of rice it takes a little less than 2 cups of water, which weighs a certain amount, so the cooker decides how long to cook it. So I can't cook brown rice in this cooker because it won't cook it for the right amount of time. If a simple cooker like this is all you need, mine was $10(u.s) for a small one (makes 3 cups of rice), and larger ones aren't too expensive.
If you go up a bit more in price you can find a rice cooker that has multiple settings to cook different types of rice, which is probably about the most elaborate machine you'd need for your use. Price goes up depending on how much rice the cooker holds too.
Depending on how much you want to spend, there are rice cookers that have digital keypads to choose exactly how you want your rice cooked and what kind of rice you're cooking, but these tend to be a bit expensive, and generally aren't used for anything but restaurants because most
of them are made to make large quantities.
You start it in the morning, and by suppertime, you have real asian rice.
Most of the ones I'm thinking of take the same amount as if you made it on a stove top. My electric rice maker takes 25 minutes. My microwave rice cooker takes 20-30 depending on the amount you make - it cooks up to 6 cups.
Btw, if you want convenience, it's really easy to make up a large batch of rice and then seperate it into portions and freeze it. I usually put each portion in aluminum foil and then steam it or boil it a bit to warm it up, it's really easy and cheaper than buying a bunch of minute rice.