Sounds like some people here don't know what they're talking about with regards to ebay rules.
On the buyer side, the ONLY thing that is against ebay rules in the context of seeking out items a seller has to sell is to ask the seller to complete a transaction off of ebay. There is nothing wrong with asking a seller to sell you something in a custom ebay listing.
On the seller side, you can end an auction early if there are no bids, or to immediately sell to the highest bidder if there's at least 12 hours left, or to end the auction altogether if there's bids but at least 12 hours left (this final option incurs an additional fee).
If a seller decides to remove something from a lot and sell it separately, that is perfectly ok to do, provided the above condition apply. It is then 100% the burden of the seller to take appropriate action at his/her end to ensure that the item being auctioned off is are as described and as pictured.
Bottom line: It is not one bit the buyer's problem if the seller removes an item from a lot and screws over another buyer...that is 100% the fault of the seller.