Would not recommend these (or similar): http://www.ebay.co.uk/itm/302323562361. I now have a rattly dash and the stereo didn't come out. Annoying as it's best to buy four, but "buy cheap buy twice" as they say.
Much better than the cheap ebay items, includes 4 Audi keys, as well as a whole host of other ones, and doesn't cut your fingers to shreds when trying to remove.
A caveat here though is that a lot of the time people have problems not because of the keys, but because somebody before them has ruined the mechanism on their head unit trying to bodge remove the unit. The amount of head units that have broken clips is ridiculous!