It's not likely, but you could possibly get your current hard drive to work again. The clicking sound is caused by the drive heads being stuck as a result of the drop to the ground. Sometimes, another good whack can get them unstuck. You'd want to take it out of the DMS casing and give it a good whack or two in the palm of your hand. This is hardly an "approved repair method" but it can work in some cases, at least temporarily.
It would be easiest to test if you have an external laptop drive enclosure, rather than using the DMS cartridge and cradle. If the hard drive is recognized, obviously you would want to run scandisk to check for errors, including a surface scan.
If you have to buy a new DMS, some sellers on eBay are selling 20GB DMS cartridges for more than a $100. If it comes to that, just spend $150 or so and get a completely NEW Audi/VW Phatbox package, which includes a 20GB DMS, USB 2 cradle and a backup Phatbox in case yours should ever fail. Otherwise, you might have luck finding someone selling a 10GB DMS, just don't pay more than $50 for that.