Thanks everybody! There are now enough pre-ordered S-100 bus extender PCBs so I ordered a batch. They should be here in early December 2013. There should be plenty of boards available so if you want to pre-order yours feel free. These are the nice S-100 bus extenders with logic probe, signal ports, grounds, indicator LEDs, fuses, etc. They are very handy for system debugging and are improved over the last version.
Thanks and have a nice day!