When I looked at the AA website earlier today it did not have a kit listed. How we they do sell individual components so you may be able to piece one together. I want a supercharger as well, and although your gas mileage suffers slightly they are better then a turbo. Most superchargers are bolt on kits plus tune software. Turbo kits are usually much more complicated and have more parts. More things can go wrong with a turbo setup then with a S/C. My car is also an automatic and I will never turbo an automatic car.
My stock 2.8l engine made 142hp from the factory. The easy mods are an intake, under drive pulleys, S52 cams, M50 manifold swap, M50 throttle body, and a good tune. The S52 cams will run fine without a tune, but to get te most out of em a tune is nessecary. As far as I know a 2.8l engine is an almost direct bolt in replacement. I think all you need to replace is the DME, and a few small things. The E36 chassis was the same. In Europe the offered a 320i which was a 6 cyl engine utilizing the same M52 block, just not bored out as much. I contemplated boring mine out to 3l, but I realized an S52 swap would be better as they are already 3.2l and made 340hp.
A former member of this forum had a 328i and he was turbo'ing it and was expecting 600hp~ when completed. His was a 1997.