So I am picking up a gift for someone and they want an Ipod Touch

I did a little reading on the Ipod Touch 5th generation and it looks like it has a bigger screen like the iphone 5 and has siri as well. What else does this thing have? I don't want to drop $250+ on this thing so was wondering if there are any Black Friday deals on this

Also what is the difference between the 4th generation all the way down to the first Ipod touch.

If I dont get the 5 I assume the earlier versions are MUCH cheaper and arent much different than the 4 etc