Context: I purchased a Mac mini 2011 (lower end) last year to move from PC to a Mac. I went for a Mac mini because I wanted to reuse my old PC's peripherals. Later however, I developed a liking for the Apple Touch Mouse, the Bluetooth keyboard, and the external SuperDrive and supplemented my Mac mini with them. Now I am wondering if the Thunderbolt display is any good (I am currently using a 20" LED display from Samsung). Obviously, this leads me to wonder if I would have been more cost effective to go for the iMac 27" to begin with.
Actual Question: What are the differences between the iMac 27" display and the Thunderbolt 27" display? Why is the sum of prices of the parts of an iMac 27" significantly more than the whole unit's price? Are there better alternatives to the Thunderbolt 27" display that will work great (fonts should appear smooth and the display should have a high resolution and a high contrast ratio) with OS X?