Hey there, yeah so I bought the part from ebay, there are many many versions of these steering wheels and they are mostly cross compatible. The one I have only came on the audi Q2. The facelifted audi 8v chassis cars (a3 s3 rs3) all have a similar steering wheel but the s-line version and above all have a flat bottom steering wheel.
I would have preferred the flat bottom version of the steering for myself but most of them were from cars that came with a virtual cockpit (full lcd speedo) and those aren't compatible with my car. I found a couple with flat bottoms that were compatible but they didn't have paddle shifters so I settled for this one. BTW my car does not have paddles originally but they are plug and play so I will gain an extra feature with this one.
There are many different types and subtypes, Audi does all leather, half leather half Alcantara, half perforated leather and half smooth leather (like the one I purchased), half perforated leather and Alcantara etc etc. prices vary wildly from 250USD to 1250USD for a premium complete steering wheel. I paid 350 for mine.
Here's a picture of the flat bottom version for sale on eBay:
Here's a pict of the one I installed in my previous car (flat bottom, alcantara and perforated leather with old style airbag):