I managed to find out about the line "Base Metal IB"
My jeweler told me that this is an SS case, plated, and the IB stands for the plating material/process.
I'll keep you in mind, if I'll think of letting it go, but don't count on it 
BTW, I opened the back, and there is another plate, like in the professional Seikos -
an anti-magnetic soft iron plate. The movement is signed "Citizen" an "Two (2) jewels".
Sorry, no pics.
G
