re: iPad pricing error,
A price tag is only an "invitation to treat" it is not a legally binding contract. If the store makes a mistake, that does not mean they are legally bound to honour it. Sometimes they will, as part of good customer service but only if it is a relatively small error and/or they will lose a small amount, before they sort it out. Tesco always honour their PoS mistakes in store (I've had no problem getting back a few pounds here and there) but they would have made a considerable loss on hundreds/thousands of iPads.
Anyway, went have a proper look at some tablets yesterday, ordered the Samsung Galaxy 8.9" tab 16GB, £279 from Currys.