There's the famous Razzo (mens and womens) beyond the Niederdorf, near Neumarkt (map link), opposite the (excellent) restaurant Bauernschänke.

I've taken a few things down there and you get your 50% in no time. The store is run strictly - no un-ironed shirts, muddy paw-printed Barbour coats thank you very much - and you will get turned away if your kit doesn't suit. But you know you'll get a good deal if you buy something