Hi,
I have fitted s-line badges on my back doors and an s badge on my boot and the one i fitted to my grill is the same fitted to all audi grills and it looks smart, got all of them from e-bay at a fraction of the price.
I originally had the smoth type grill but got the slatted type to fit the s-line badge as i think a stuck on one would look snidey on a smoth type grill and this is how i done it.
you discard the two metal pieces that come with the s-line badge that are used to attatch it to all other audi grills, i drilled a small hole in each of the plastic sections on the back of the badge, drilled two small corresponding holes through the grill were it cant be seen and simply threaded through a length of inner electric cable ( the green,blue or brown sections) a ten minute job that makes a nice job, looks like any other audi front grill s-line badge and is easily removed to stop any over enthusiastic mechanic ripping it of when cleaning your a2.
i will try and get my son to take some pictures later on and will try to post as to give an idea of what im meaning.