I have a 27" iMac. The price in the UKfor the TB display is £899.00 Don't get me wrong, I love my Apple stuff, but that knit of money for a display..fast as it may be. Is just too much money.
You can do nearly as well, for about half the money, unless you are determined to use the TB connection.
I'd like another monitor for my bedroom to use with my MBA/ MBP, but close on £1000? Nope.