I think you'd be doing good if you found a 100B in trade. There were only 100-150 ever built. It's a lot more rare than a IIC+, since they made around 2500 of them, I believe. I've got a 100B and I'll never get rid of it. Really great sounding amp. The market values are probably similar though so it'd be a fairly even trade. Hardwood and wicker is always a bonus.
I think someone else here or on TGP was also looking for a 100B. I haven't seen any available lately.