A thread about this was started over at sega8bit a while before this one was and pretty much the same stuff was being said! If the guy wants to seperate carts and manuals to charge more on postage, if the same person gets both auctions they should just ask them to be combined - the seller can hardly refuse at the price the stuff is going for! And if they do refuse, undoubtedly the buyer could through paypal get back some of their money. Someone mentioned earlier that they hoped it was a dummy bidder so they would have to pay high fees - but they wouldn't if that were the case because you can submit that to ebay - it happend to a friend of mine recently when one of these idiotic Nigerian Scammers bid a huge amount at the last second on an expensive phone she was selling. She had to tell ebay but they cancelled that guys user account and the next highest bidder automatically became the winner - although they then had the option to pull out.
As for why people are bidding so much? People who know the NES scene will tell you that one of the major problems with it is that in the last couple of years a lot of 'rich kid' collectors with wealthy mummy and daddy's have appeared on the scene because 'retro' is viewed as cool to a lot of people. They have pushed the prices up no end, and a lot of them are like 12 - 18 years old, not spending their own money or caring!
The NES scene is totally fu**ed up for a number of reasons like that, and many collectors don't care about box and manuals because unlike - say - PCE / SMS / Genesis etc. which all have hard cases, the NES all have cardboard boxes meaning tha getting a full collection of boxed IN GOOD CONDITION games is near impossible, and those that actually do try end up spending obscene amounts - a HELL of a lot more than this auction. I know personally of a guy who was selling privately in the states last year of around 300 mint boxed games (half the number of games here), and he was getting offers upwards of $50,000 and rejecting them. So the general consensus among most of the genuine collectors is that they collect all the games first if possible, and they view that if some have boxes and manuals it is a bonus, then they try to pick up spare boxes and manuals cheaply as and when they can to build that side of things.
It all depends on what a persons collecting aims are I suppose - there are three types of collectors IMO, the collector who displays all their stuff nicely and aims to get EVERYTHING to have a full collection, the collector who buys games they actually like to play and is more of a player than a collector who is not interested in collecting for collecting's sake, and the collector who is a bit of both - probably not as OCD as the firs collector but enjoys to play the games a lot too, probably more so than the first guy who would worry about things losing their 'mint' appeal

.
So anyway, I certainly wouldn't pay as much as this auction seems to be reaching, but being a NES collector and knowing the scene pretty well it doesn't surprise me in the least the way this auction is going.