I bought an inexpensiver rice cooker to see how often I would use it before getting a more expensive one. The rice consistently sticks to the bottom, which I attribute to the heat being seeming to be too high. Is this to be expected, or a factor of the quality of the machine? It doesn't affect the flavor of the rice, just a layer on the bottom that needs to be soaked off.
Are you trying to serve it immediately after the cooker dings/clicks/buzzes? That may be your problem. Let it 'rest' for about 10 or 15 minutes. I have never fully understood why the rest works, but I would guess it's very similar to allowing meats to rest after removing them from a heat source, by allowing moisture to redistribute.
It could be just the quality/brand of the machine. Most rice cookers now seem to come with non stick inserts. I purchased a inexpensive Panasonic at LNT for $40.00 a few months ago. Works beautifully and is non stick. It's a 10 cup version. They also had a 5 cup version for less money, but was not a non stick. I'd go with some of the better brands such as Panasonic, Sanyo, and Zoji.