Posted By:
Brian McQueenI've seen a bit of this as well. The past 2-3 months, I've seen abnormal groups of c46s, e90-1s, t207s, e106s and e90-3s all on Ebay at once, all by the same seller and each card ending within a minute or two of the previous one. These consisted of near-sets in some cases and some of the cards listed were scarce ones of of their respective issues as well.
As a seller, I can think of a few examples of why it's beneficial to split lots up and auction them individually like this -
1. you make the cards available to all bidders, not just those that can afford the entire lot. This increases competition on individual cards and leads to some of those really insane prices that you see prewar cards get on occasion.
2. There's a common line of thinking that it's better to buy in bulk as the cards come cheaper that way. If you sell the cards individually, each card goes for it's full market value since more people will be bidding on it.
3. You attract new bidders to the set as a whole. You never know when a bidder will simply decide to start the set that night and try to go after all the cards to see how far he can get on the whole thing in one sitting. I did this with a large group of 87 c46s that were auctioned off individually. I started off just winning the first couple of cards and before I knew it, I had been sitting at my desk an hour and a half trying to win all the cards I could. I ended up with 65/87 cards doing it this way and still have all of those even to this day 
Of course, there's drawbacks to doing it this way too - the postage and Ebay fees are a killer for this many items. Plus, you all of a sudden have to worry about a couple (few dozen??) transactions instead of just one. I guess the seller has to decide whether the benefits outweight the costs of auctioning their cards off individually this way. You're right however, when other people then decide to sell off THEIR own e106s, e90-3s, etc...then the market becomes overly saturated with the cards. In this case we actually have a scenario where the supply overtakes the demand and then prices fall. The big collectors who really need the specific card already have it by the time the third, fourth and fifth example surfaces on Ebay within a few weeks/months of each other. Prices then end up dropping due to the reduced amount of interest.
I'm noticing this with e90-3s right now....last week when I checked, there were 22 e90-3s on Ebay all at the same time. This is supposedly a really tough set but you wouldn't have known it just by looking at all the cards that have been available the past few months. I've noticed that Ebay has been swarmed with these ever since April/May so sooner or later, those market prices for the individual cards will really start to take a hit as I know they've been struggling already (except for maybe the Gandil).