Originally Posted by ax0n

No other cassette would fit on that freehub body? Does it have a completely proprietary body size or spline design?

Anyhow, when I decided to get a cheap winter wheelset, I got a Shimano MegaRange cassette for $15. It was a take-off from a brand new bike. The buyer wanted a different cassette. I could have gotten a new cassette as cheap as $20 installed. I bought it and a cheap Alex Rim/Shimano Freehub wheel. I think total cost was $60 out the door after taxes. I've never been charged for installation of parts I buy at the shop.

Anyhow, your best and possibly cheapest bet is to hit the bike shop. They can remove the broken cassette, and see what needs to be done to fix it. If another cassette will fit, they might have one or know where to get one. Worst case scenario, you'll need a new hub or whole wheel.