Run, don't walk to the Englehorn Sport logistics center in Mannheim-Neckarau. Every year they open up their warehouse for some really ridiculous discounts. I just bought a beginner snowboard, bindings and boots for 190 Euro (board reduced from 150€, Salomon boots reduced from 125€, bindings down from 100€). These tents are in the parking lot and to save yourself a whole lot of trouble, bring cash for here they don't accept EC cards.
Here is the drama - going down into the warehouse. It is jammed packed full of greedy bargain hunters. It is so crowded they actually starting limiting people who could go in and out. When I left (at 12, I got there at 10.10 a.m.), there were about 75 people waiting to get in. As usual, the Germans do not know how to arrange lines, so it was just a clump of people, 10 deep, all in all maybe 200 waiting to pay at 4 or 5, yes, cash registers. I found a great pair of ski pants reduced from 140€ down to 30€ and after waiting 15 minutes, moved 1 cm and spun on my heels and left, went to the bank, got some cash and just paid for my snowboard kit and left the trousers on some rack! The mob, the crowd, the disorganization, the danger... not worth it IMHO (unless you just want skis, boots, snowboard, etc.).
They have not only winter sport articles, but blouses, blazers, shoes (not many), kids stuff all at 80% or more off.
Engelhorn Logistik Center
Fabrikstationstraße 40
68163 Mannheim
Easy to reach - take the 1 towards Rheinau and get out at Lettestraße. From MA Hbf, it is a 9 minute train ride, then 5 minutes to walk to the warehouse.