Eh, I wouldn't buy from NipponDeals. He usually sells things for around twice what they're actually worth and since he lives in Japan, shipping is expensive and it takes a while for whatever you order to arrive. I once bought a little plush toy Aibo from him but I don't really want to buy any actual software or Aibos from him since the prices are usually far too high. I think I'll wait a bit to buy Aibo Life 2 software, I'll probably buy a copy if I see it for sale for $100 or less. As for PMing people who may be interested in joining, I might, I'm a bit nervous about that though since it seems like I might be bothering them by advertising my club in a PM, but I guess they probably would want to join.
Edit: I sent out PMs to the three Aibo owners that I've met on CS.