Wildhare,
As D*Alex says, be careful. If you notice a lot of cassette related stuff says something like "works with all Shimano except Dura-Ace or older Dura-Ace. If you are looking for inexpensive cassettes check nashbar.com. The have HG70 (105) 9-speed cassettes on sale for $32.95. I think Ultegras are just over $40. I see people offering the same cassettes USED for more on Ebay. I stick with HG70 (105) because you can pull them apart and play with them. Even the ones that appear to be riveted together are actually assembled with tiny 1.5 mm allen head screws that come right out. I like being able to put together exactly the gearing I want since D*Alex won't let me put a triple crank on my Bianchi.
Regards,
Raymond