They are ridiculously high - the $750 pricetag is way beyond a casual fan's price range. If those were the only shows that they are doing related to the 50th anniversary, then in some way it's understandable - even though thousands of people will not pay those prices.
Keith Richards hinted today that they might do more shows towards the end of the year and in 2013. London and Newark can't be it. Hopefully ticket prices for those shows will be much more lower, cause with these prices, they entered Barbra Streisand territory.