you can get the fob from ebay
take your apart and make sure you get the right one - p/n is inside it. the key breaks into 2 parts. the front end with the transponder can be opened by prising up the audi rings badge and there is a small screw inside.
i bought this one from ebay as my blade was snapped - 12 quid from ebay and 15 for cutting the blade to match from my mechanics key
http://cgi.ebay.co.uk/ws/eBayISAPI....m=220249521502&ssPageName=STRK:MEWN:IT&ih=012
you can also buy the whole key from ebay - costs a bit more 40- 60 pounds.
recoding from dealer for me was FOC as I bought a full key from them at £105
recoding on it's own at Chester Audi is £25, other dealers can charge £50 and maybe more
the key front end with blank blade and transponder inside I bought from ebay was recoded fine by the dealer - free luckly as I had bought a full key as mentioned above.
programming the remote to open the doors can be done as can the blade cutting, swapping the blades, and pairing up a new front end and remote. only thing as you recognise is the transponder recoding - they do all the keys at the same time.
i had to show my drivers licence and V5C as well as a utility bill for the recoding