Run, run, run. That eBay deal is NO DEAL.
There is a concern about using external subs with the model ll that is different from the original PAS. When you don't use the Bose B1 cabinet, the crossover point is almost doubled, so you get a very different response from the tower. I'm sure this is to protect the tiny tower speakers from an inexperienced user that thinks he knows more about bass than the Bose team.
Be careful about buying "pieces" of a system. The pedestal unit is integral, as many have said b4. The Model ll towers do NOT fit the Model l pedestal either.