22shot, you have a DLV or NSFK dagger- a pic of the emblem(s) on the top of the scabbard throat will clarify which. The DLV (German Sport Flying Organization) became the NSFK (National Socialist Flying Corps) when the Third Reich dropped the pretense of not re-building their Air Force
Yosemite, I agree with 22shot that your SA dagger is authentic but it does have some condition issues- the blade in particular has been thoroughly scrubbed and the maker's logo almost completely obliterated. The only way to ascertain value would be to offer it on one of the dagger sites and see what it brings... the maker's logo E.P.&S. is Ernst Pack and Sohn- that figure is actually a blacksmith swinging a large hammer which is poised over his back.
If you look, the M on the crossguard is actually Mi- this is the unit mark for the SA Gruppe Mitte (there were 27 groups).