Was in Berlin only a month ago, found the follwing:
Hein Gericke (2 shops), Louis, Polo, Bikers Miles and Studio Helm or Go To Helm (can't remember which?)
Depending where you're travelling from, prices can be cheap. Generally cheaper than Britain, with a large variety of brands that are not sold here. The euro has resulted in some considerable price hikes. Dark visors are 50 euros, not £50.00.
If travelling from the UK and planning on buying any HG gear, check out the prices in UK first, can be cheaper.
If ever visiting Hamburg, all the main bike accessory shops are near Hammerbrrok S-Bahn stop. The Louis shop has a very good discount shop in a separate building to the rear of the main showroom.
In any of the outlets mentioned, you should be able to kit yourself out with known brands at good prices.