Honestly, as long as you have something which has at least two temperature options (high/low) and can be turned off without having to unplug it, you'll be fine. Remember that you need to half-fill the pot to use it efficiently, so don't get anything that's far too big for your needs. I like to cook extra so that I can save some in the fridge or freezer, and that might work best for you. My 4.5l is just fine for two people/two meals and can easily fit a whole chicken or big chunk of meat to cook.

Having had a quick look on Amazon.com, I would go with this one: http://www.amazon.com/Hamilton-Beach-33141-4-Quart-Cooker/dp/B000A1FFPO/