Foie gras has come way downmarket in the last 10-15 years. While nothing compares directly to real, French goose foie gras, duck foie gras is a damn good substitute and a fraction of the price. Also, if you are using it as a spread or stuffing, you don't need to spend extra for whole chunks (or a whole liver), get the mousse instead.
Here's a good mailorder source if you want to try it:
http://www.dartagnan.com
I always keep a tube of this mousse of duck foie gras, sauternes and black truffles in my fridge:
https://www.dartagnan.com/item.asp?item=PTEFG036