To answer your question Andrew yes it will be honored, Amazon already said they would and they cannot charge you an extra 100 quid , the law does not allow it. They don't have to honor mistakes by law but they cannot cancel your order and charge you more. I really hope you get a machine mate and my comment was more aimed at the Op than you, you asked a valid question, the op just bragged.
I can assure you Andrew it will get honored. A thread was started i while ago about this so i contacted Amazon and they said with 100% certainty that they where going to honor the orders at £199. Not that many people managed to grab the misprice so its not like Amazon is losing millions, in fact i bet the extra 100 quid was Amazons markup, so all they lose is profit.
On September 13th, during the Nintendo presentation of the European release date (where Nintendo stated that every shop decides their own price for Wii U), they put the Wii U up for preorder again, starting at £199.99 for a very short period of time before raising the prices. They confirmed that they will honor these prices, so there are a handful of lucky people who get their Wii U a bit cheaper.
It wasn't a misprice in September. Every onlineshop wanted to bring their preorder page online as soon as possible on September 13th. And since Nintendo didn't name a suggested retail price during their announcement that day, it took a few hours before they all settled at similar prices.
I think Nintendo may have told them to take it down. Amazon didn't know that there would be two models available and so would be impossible to pre order. Imagine the mess they would have to go through checking which customer wanted which model. Was easier for them to cancel and wait.
i got it also along with everoyne on neogaf reason why its allowed cas in june it was listed as 199 but then cancelled but in september it was relisted for 199 before going up to 299 making the june order walid again took awhile to get through on the phone but yes for the next 6 year ill remeber this till nintendo next console