The BAM case is to my recollection a soft shell case, but waterproof material. It is also quite large. Protec make a more compact and affordable soft shell case (about 30% of the BAM price). They also make a soft shell compact case for curvie sops. Most of the hard shell sop cases that are good are very expensive and also seem to be larger than necessary, though there are some cheap ones around - I wouldn't put my horns in them.I don't own one, but I heard very good things about the BAM trekking sop case.
If you have a straight sop, you might also want to check out the Walt Johnson hard case (single neck sops only)