There are numerous army surplus suppliers around munich town center
One by the mc donalds on leopoldstr (but run by 2 strange turkish women)
The one down the side of
Hauptbahnhof is ok (run by a mad asian woman - arnulf str)
Or there is a place that is so unhelpful on dachauer str.
If you want some Dr Martens, you can get them.
There is a shop I think on Herzogspital Str who carry a large amount of DM's, but they aint cheap
HTH
P