You are quite correct, 40 Super is NOT the same as 40 S&W (not even close). A 40 Super is actually an improved 45 mag case necked down to accept 40 cal bullets. Its a smokin' hot 40 round! FYI: it is 50 to 200 fps faster than the 400 Corbon. The 400 CB is a standard 45 ACP case necked down to accept a 40 bullet.
YES, 40 Super can be found at Double Tap Ammunition. 400 CorBon can be found at Corbon. Tell 'em JR from LWD sent ya