Well, the differences for Denon are spelled out in the first page of the thread, "the official 2013 Denon E/X series avr", etc. Very good reading and explanation for the denons.
Don't know about the other manufacturers.
If you are looking at internet pricing, I just bought a Denon x3000, receiving it Monday. So, the shipping time to me was about a week (across country--east coast to AZ). PM me for pricing and store name if interested.
I set up Audyssey Tuesday night. Very impressed with it.