i fitted one myself a month or so ago and i am so happy with it - elbow is permanently moulded to it!!
anyways, i got a genuine one from ebay from this guy
he has another for sale at the minute, its at Ł1, has a day left
i got mine for Ł80 and fit it within 30mins
the seller is 100%, package arrived quickly and as described
i would advise anyone who hasnt got an armrest in their a3 to bid on that above - bargain!
they are Ł120+ from audi and god knows what for fitting
to fit you DO need to cut your centre console but the armrest covers the area neatly - i can post up some "how to" pics if needs be
grab yourselves a bargain before i do and sell it on for a profit :P