I really wouldn't take too many of those Ebay postings seriously. If I read correctly, somebody is trying to sell one for $100,000? Give me a break.
I'd venture a guess that a huge majority of both the sellers and bidders are people just screwing around, or a kid who has no idea how much he is bidding on something, and has no inention or ability to actually pay.
It was one thing when parents were buying those Tickle-Me-Elmos for like $300, but no parent is going to spend $3,000-10,000 on a video game system that will not be in a shortage in a couple months, and therefore will be available at a normal store price.
I am in no rush to buy my 360, from what I remember from the first Xbox, several improvements were made and glitches fixed as they continued to release the system, as opposed to the first wave that was released.