Hello 'box42',
Sellers can pull their items in certain circumstances, and ebay can also remove items for
various reasons.
The following link will tell you about sellers ending listings early:
http://pages.ebay.ca/help/sell/end_early.html#reasons
Whilst it is certainly true that sellers occasionally end a listing at the last minute if they are
not getting their price and fear they may not get it by the end of the auction, there are just as
many times when the item is found to have something wrong with it, not working, etc.
If you had put a bid on it, even the most minuscule possible, and the listing was ended by the
seller, you would have had notice of this. If ebay had removed the listing, they'd have sent you a
note saying it is not longer available.
Sellers need to cancel bids before ending listings early. You can read about it here:
http://pages.ebay.ca/help/sell/manage_bidders_ov.html#canceling
And if you want to know why ebay removes listings sometimes, there's this:
http://pages.ebay.ca/help/sell/questions/listing-ended.html
Hope some of that helps.