Toxic, we are talking carriers here, not calipers. The Audi parts price is per pair for the MkV chassis not the MkIV chassis a la old Leons/Ibizas in the Seat section. Actually the discs/pads aren't a bad price either. I bet you could get some discount for ordering all 3.
Orginal pads fit fine since the caliper is same, its just out on a larger radius.
Braking difference - far less snatch on very light braking than I used to get with 288s, although that could be down to the pads as well. Haven't thrashed them on a good road session yet. Look better under my alloys