Photodisc (or Getty Images, now) is gonna cost ya. The 10 mb file (5x7 @ 300 dpi) is (Jesus!) $120! Gone up a bit since I worked there.
If you're looking for cheap/free, do some digging on google and you can come up with some co-op style places. The quality varies WILDLY, natch, but you might find something you can use for free or really, really cheap.
Here's a link to jaguar fur photo at
istockphoto. When you register, you get two free download credits, so you could DL this pic and see how it is. It looks blurry and dark, but... A nice plus is you can make a request on their forum.
splode