there are and there arent.
the issue is that most ppl find that the price of the 330 doesn't justify buying it, you might as well go for the 335. So a lot of ppl find themselves either going for the 323 or 335.
But back when the 330i was the highest (aside from the M3) then it was more abundant. So if you look anything 2006 and before, you will find them. 2007 there are still a few. But afterwards its become more and more scarce.
If you read Chinese, start off with www.28car.com
it's basically a used car database. (even if you don't read chinese, the simple instructions are, go to the type box on the rightmost side of the webpage [NOT the two type boxes at the very top], and type in the model number, and press the 2 chinese words beside it (it says search).
Hope this helps